Hi @luke_larose! Thanks for writing in.
Yes, this is a very unfortunate issue with the UI engine that FormIt uses for the desktop app. ☹️ The "black triangles" issue, as it's affectionately known internally, is especially frustrating because we've not been able to isolate exactly what causes it, and there's no workaround other than saving the model and restarting FormIt.
One thing we have learned is that it may be related to one of the plugins. I see from your screenshot (thanks!) that you've got some plugins installed. They're super powerful! Unfortunately, they're using a web-based rendering engine that may have a weird timing collision with the desktop app and one of them may be causing the black triangles to happen more frequently.
Would you mind telling us what plugins you've got installed? There's one in particular - Properties Plus - which is likely a culprit since it does some calculations with every selection. I wrote the majority of our plugins, so it pains me to suggest disabling one or more of them, but it might be worth trying to see if it mitigates the problem. The issue is not with the plugin itself, but the engine that displays it along with the rest of the desktop user interface.
Let us know what plugins you're running, and if the set includes Properties Plus, maybe try uninstalling it and seeing if the issue happens less frequently?
Josh Goldstein
Senior Product Manager