We had to go back to a backup after a file we were working on displayed the behavior described in this discussion: Relationship Graph Flashing
Here is a video of this issue:
The problem occurred while working on a Windows computer on a file hosted on FM server. Any computer connecting to the file then gets the same behaviour (even from a mac computer as on the video).
Workstations were using FMPA 15.
Can someone from FileMaker confirm if the issue is known, what provokes it, ways to avoid it, if it is fixed in any of the versions that are under support or if FileMaker is working on it (or not working on it).