Hi, so glad you posted this! I had this exact issue. The fonts also appear to change as well when it occurs. However, it does not just occur on table exit. I thought the same thing until just last night I was scrolling through tables in the PBX interface and the wheel images disappeared right in front of my eyes! My storage on C:\ is also "low" (see screenshot below). https://winaero.com/clear-temporary-files-automatically-windows-10/ Good news! I disabled Windows 10 "Storage Sense" and let PBX sit there for the amount of time when the issue usually happens (after 5-10 minutes)...and success! Problem solved.
StorageSense activity logs are found here: C:\Windows\System32\LogFiles\setupcln\setupact.log
For reference, here is a video of the issue when running PinballX v5.15 on Windows 10. Perhaps PinballX can write an event to the log file when this issue is detected referring to the solution? Example/ "Windows Temp File detected as missing: C:/users/%user%/appdata/local/temp/file.jpg Consider disabling Windows Storage Sense or freeing up your C: drive"