Client Product and version: FileMaker Pro Advanced 18.104.22.168
Server Product and version: FileMaker Pro Server 22.214.171.124
Client OS and version: macOS 10.12 Sierra ( Spaces enabled under Mission Control - Displays have separate spaces )
Server OS and version: macOS 10.12 Sierra
Client Hardware: rMBP 15" 2012 with External display via HDMI
Server Hardware: MacPro on a 1Gbps up/down connection
Description: When editing a remote FileMaker solution the FileMaker windows do not redraw properly (GUI) when editing more than one window on a dual monitor system (one FileMaker window on each monitor). The failure to redraw occurs on either the rMBP display or the external display (HDMI). In some cases FileMaker will not visually indicate when a layout element is selected but the values will show up in the Inspector. This problem did not occur under OS X 10.11 El Capitan.
How to replicate: In the same remote FileMaker solution open two windows and put one window on each display. Then put both windows into Layout Mode and begin to edit the layouts, go back to browse mode in one window and then copy-paste a layout element in the window still in Layout mode. I have had trouble finding the exact steps to replicate it but eventually happens after 15 minutes of aggressive editing (working across multiple layouts while copy-pasting elements and toggling between browse and layout mode). Also seems to occur when editing a local solution while a remote solution is open (affects both solutions). Again, this problem did not occur under OS X 10.11 El Capitan.
Workaround: Only have one FileMaker window open at a time.