To reproduce, just run Maps, right-click somewhere, and select 'Route from here'. The routing panel to the right of the map opens, but half of it is not visible, seemingly covered in some sort of odd white...layer. If you then resize the window, the whole routing panel disappears behind the white layer, and the window stops being square (the right hand side of the window sort of bleeds past the X button, is the best way I can describe it).
Will attach a video.
Proposing as a 29 Final blocker, per criterion "All applications that can be launched using the standard graphical mechanism of a release-blocking desktop after a default installation of that desktop must start successfully and withstand a basic functionality test."
Created attachment 1492297 [details]
video of the bug occurring
Additionally, if you right click and select "What's Here?" *after* triggering this bug, gnome-maps crashes. If you do "What's Here?" *before* triggering this bug, it works. I'll attach a traceback from that crash.
Created attachment 1492639 [details]
backtrace of the crasher that can be triggered after triggering this bug
I was able to reproduce this bug.
We sadly don't have anyone working on gnome-maps anymore in Fedora, and I am (as the ticket is assigned to me) right now occupied with fixing various gnome-software regressions in F29 that are all much higher priority. I wouldn't recommend blocking the release on this.
Remember that one way to address a release blocker is to remove the app...
@adamw: gnome-maps version?
I can't reproduce this with gnome-maps-3.30.0-1.fc29.x86_64.
3.30.1-1.fc29. Dunno why you're on 3.30.0.
I can't reproduce with gnome-maps-3.30.1-1.fc29.x86_64 either.
Actually those two recent versions of gnome-maps work great here — display is snappy and the routing seems quite good.
I can't reproduce the bug in the description and video. I can reproduce the crash in comment 2.
Discussed during the 2018-10-15 blocker review meeting: 
The decision to classify this bug as an "AcceptedBlocker" was made as it violates the following criteria:
"All applications that can be launched using the standard graphical mechanism of a release-blocking desktop after a default installation of that desktop must start successfully and withstand a basic functionality test".
We note that dropping the app from Workstation is acceptable if a fix is not available.
I can't reproduce it here either. Can one of the people who is able to reproduce it report it upstream at https://gitlab.gnome.org/GNOME/gnome-maps please? Thanks!
Ahh sorry never mind, I see it's already reported at https://gitlab.gnome.org/GNOME/gnome-maps/issues/131
I also cannot reproduce this bug. Will send this out to the list to request more testing.
The Workstation WG discussed this bug and was against holding the release up for this bug. However, upstream are looking at it so we can winnow down the cases where it does reproduce. Some users report this working fine under intel + Wayland, so it doesn't seem to be universal. It should be possible to fix in an update.
This link may be useful: https://gitlab.gnome.org/GNOME/gnome-maps/issues/131#note_348400
Discussed during today's blocker review :
#agreed 1637751 – RejectedBlocker AcceptedFreezeException – After much deliberation and hearing from stickster as representative from the Workstation WG, we have unanimously decided to not block the release on this bug, based on the fact that 1) the bug is not universal, 2) the fix may destabilize other things, and 3) it seems overly-zealous to block the release on this bug. We accept it as a Freeze Exception in case a fix comes about soon.
Does this issue remain in version 220.127.116.11 that is the current in f29?
Yes, gnome-maps-18.104.22.168-1.fc29.x86_64 has this problem. Right click on map, choose "route from here" as described, and I get a white box on the right with no user interface elements at all. Just a white box. I can't resize the window on the right side but if I resize from top,bottom, or left sides, the routing UI appears.