Chrome Version       : Version 60.0.3112.113 (Developer Build) 
OS Version: Built on Ubuntu , running on LinuxMint 17.3 (64-bit)
URLs (if applicable) : fanfiction.net, billpay.captialone360.com
Other browsers tested:
  Add OK or FAIL after other browsers where you have tested this issue:
     Safari 5: Don't have.
  Firefox 4.x: With the firefox I have: OK, same functionality as two days ago. (Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0)
     IE 7/8/9: Don't have.

What is the expected result?
Functional scroll bar showing on right of iframe area.

What happens instead of that?
-Fanfiction.net RTF-edit iframe doesn't show vertical scroll bar. But seems to respond to mouse actions as if the scroll bar is there. Though this is very difficult without seeing where to click or drag.

-captialone360.com bill pay iframe doesn't show vertical scroll bar. Does not respond to mouse actions as if scroll bar is there.

In both cases the inner body can still be scrolled by keyboard as normal by clicking the body background, then pressing the arrow keys or page up/page down.


Interesting notes:
When I view the page in developer tools, the iframe gets it's scroll bar and the outer page loses its scroll bar.

When I load the inner web page of the bill pay in a separate tab, it behaves normally.

When I try this trick on fanfiction.net I realize that the contents of the iframe are dynamically assigned from a textarea field, so... it might not be an example of the same problem, but it seemed to happen with the same update.
 

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	Screenshot at 2017-09-15 08:50:02.png 150 KB View Download