Below is manual regression range:

Good build: 71.0.3575.0 (Revision: 597883)
Bad build: 71.0.3576.0 (Revision: 598282)

You are probably looking for a change made after 586871 (known good), but no later than 586882 (first known bad).

CHANGE-LOG URL:
https://chromium.googlesource.com/chromium/src/+log/af9906ef20544c312f97d8774e045139758da24a..33d2f351e23d3db6fbbee5d0835aeaffd997e910

Suspecting: https://chromium.googlesource.com/chromium/src/+/33d2f351e23d3db6fbbee5d0835aeaffd997e910

@rbpotter: Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

NOTE:
1. Provided suspect through 'Chromium bisect' script because unable to perform bisect using 'per-revision' bisect script.
2. Tried performing 'per revision' bisect on multiple Windows and Mac machines but unable to perform the same since getting "RuntimeError: We don't have enough builds to bisect." error.
3. This is also reproducible on Linux (14.04 LTS) OS.

Kindly review the attached screen-cast for reference.

Thank you.

Deleted: Actual behavior.mp4 447 KB

	Actual behavior.mp4 447 KB View Download

Deleted: Expected behavior.mp4 406 KB

	Expected behavior.mp4 406 KB View Download

Adding release blocker label for this issue.Please reduce priority or remove if not the case.

Thank You!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aa730994107b1bef054c04a2ee339fdfe637a55e

commit aa730994107b1bef054c04a2ee339fdfe637a55e
Author: rbpotter <rbpotter@chromium.org>
Date: Fri Oct 12 18:13:49 2018

Print Preview Refresh: Fix enter key blocked in pages input

Bug:  894350 
Change-Id: Ic5cde2aef449e745e1301ee0c09b6e9ad50308e3
Reviewed-on: https://chromium-review.googlesource.com/c/1278534
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599291}
[modify] https://crrev.com/aa730994107b1bef054c04a2ee339fdfe637a55e/chrome/browser/resources/print_preview/new/pages_settings.js
[modify] https://crrev.com/aa730994107b1bef054c04a2ee339fdfe637a55e/chrome/test/data/webui/print_preview/pages_settings_test.js
[modify] https://crrev.com/aa730994107b1bef054c04a2ee339fdfe637a55e/chrome/test/data/webui/print_preview/print_preview_interactive_ui_tests.js

Update:
Rechecked this issue on Windows(7,8,8.1,10), Mac(10.13.1, 10.13.6, 10.14) and Linux(14.04) machines using latest Canary #72.0.3581.0 and issue is fixed. Hence adding TE-Verified labels.

please refer the attached screen-cast for reference.

Thank you.

Deleted: Fixed_behavior.mp4 528 KB

	Fixed_behavior.mp4 528 KB View Download

[Auto-generated comment by a script] We noticed that this issue is targeted for M-71; it appears the fix may have landed after branch point, meaning a merge might be required. Please confirm if a merge is required here - if so add Merge-Request-71 label, otherwise remove Merge-TBD label. Thanks.

CL landed shortly after the branch cut. As noted by the reporter, this should be fixed for 71. The fix should be safe to merge and is verified by automated tests added in the same CL.

Your change meets the bar and is auto-approved for M71. Please go ahead and merge the CL to branch 3578 manually. Please contact milestone owner if you have questions.
Owners: benmason@(Android), kariahda@(iOS), kbleicher@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/82c07f1d3fa81f2eac1d9e227e9adc3e23ac162e

commit 82c07f1d3fa81f2eac1d9e227e9adc3e23ac162e
Author: rbpotter <rbpotter@chromium.org>
Date: Tue Oct 16 18:51:01 2018

Print Preview Refresh: Fix enter key blocked in pages input (M71)

Bug:  894350 
Change-Id: Ic5cde2aef449e745e1301ee0c09b6e9ad50308e3
Reviewed-on: https://chromium-review.googlesource.com/c/1278534
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#599291}(cherry picked from commit aa730994107b1bef054c04a2ee339fdfe637a55e)
Reviewed-on: https://chromium-review.googlesource.com/c/1284056
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/branch-heads/3578@{#52}
Cr-Branched-From: 4226ddf99103e493d7afb23a4c7902ee496108b6-refs/heads/master@{#599034}
[modify] https://crrev.com/82c07f1d3fa81f2eac1d9e227e9adc3e23ac162e/chrome/browser/resources/print_preview/new/pages_settings.js
[modify] https://crrev.com/82c07f1d3fa81f2eac1d9e227e9adc3e23ac162e/chrome/test/data/webui/print_preview/pages_settings_test.js
[modify] https://crrev.com/82c07f1d3fa81f2eac1d9e227e9adc3e23ac162e/chrome/test/data/webui/print_preview/print_preview_interactive_ui_tests.js

The following revision refers to this bug: 
https://chromium.googlesource.com/chromium/src.git/+/82c07f1d3fa81f2eac1d9e227e9adc3e23ac162e

Commit: 82c07f1d3fa81f2eac1d9e227e9adc3e23ac162e
Author: rbpotter@chromium.org
Commiter: rbpotter@chromium.org
Date: 2018-10-16 18:51:01 +0000 UTC

Print Preview Refresh: Fix enter key blocked in pages input (M71)

Bug:  894350 
Change-Id: Ic5cde2aef449e745e1301ee0c09b6e9ad50308e3
Reviewed-on: https://chromium-review.googlesource.com/c/1278534
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#599291}(cherry picked from commit aa730994107b1bef054c04a2ee339fdfe637a55e)
Reviewed-on: https://chromium-review.googlesource.com/c/1284056
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/branch-heads/3578@{#52}
Cr-Branched-From: 4226ddf99103e493d7afb23a4c7902ee496108b6-refs/heads/master@{#599034}