I've noticed sometimes the icons take a while to show. Other times they never come up.

What version of Chrome OS is this happening on? Chrome version isn't enough for us to know what specific build this is occurring with.  I'm unable to reproduce this problem on Chrome OS 10663.0.0 (which has Chrome 68.0.3425.0).

Due to badness on canary I just reimaged my device and setup the container fresh. After installing terminal, I installed gimp, and I'm getting the placeholder icon.

Version details: 
Google Chrome   68.0.3425.0 (Official Build) dev (64-bit)
Platform:       10663.0.0 (Official Build) dev-channel eve
Termina:        10669.0.0

Following that powering off, signing in, starting terminal again caused the proper gimp icon to appear.

Versions are all the same.

I'm going to add more logging on the Chrome end of things, in concierge and in garcon regarding icon loading. I've been unable to reproduce this problem and the current logs simply don't give enough information to point to anywhere to look for a problem.  I'll update this bug after I do that.

I did realize one issue with this....if the desktop file gets written before the icon file and we then get the application update message...we then may not find the icon file right away and then it won't show up until the next restart.

I finally hit this...after I installed gimp it showed the penguin icon. There was one log entry from garcon for a icon request (and there should be 2). There's only the 1.0 scale icon written into crostini.icons. No other errors anywhere.

Installed gedit..exact same thing happened...and also with a few more apps. So this is not the race condition I mentioned in my last comment (it wouldn't happen that many times, and I'd also see the icon requests in the garcon log).

Dug through the code...found the bug...fix coming very shortly (it's an incorrect variable name from a copy/paste of a block of code).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/555b6835091521a9e9451bd58baa908c5f9f146f

commit 555b6835091521a9e9451bd58baa908c5f9f146f
Author: Jeffrey Kardatzke <jkardatzke@google.com>
Date: Thu May 17 02:04:31 2018

Fixed bug where Crostini icons didn't always load

This is an obvious coding error, the wrong variable was used for
checking if an iterator was empty. Depending upon if a specific bit was
set in that random memory location, then we'd get the right/wrong
behavior.

Bug:  842196 
Test: Icons load (although they usually did before)
Change-Id: Ie52747f0b03e82ba2915df3f8ce9198a9a22452f
Reviewed-on: https://chromium-review.googlesource.com/1062199
Reviewed-by: Timothy Loh <timloh@chromium.org>
Commit-Queue: Jeffrey Kardatzke <jkardatzke@google.com>
Cr-Commit-Position: refs/heads/master@{#559396}
[modify] https://crrev.com/555b6835091521a9e9451bd58baa908c5f9f146f/chrome/browser/chromeos/crostini/crostini_registry_service.cc