Syncing issue with windows 10

[mariokleiner]

What Ian says. Also for additional diagnostics:

Sync failure on a dual display setup

As a diagnostic aid in the three most recent PTB 3.0.17 betas since february 2021, there is one new visual way for a human observer (but not for PTB itself) to find out if sync failure is due to interference by the desktop compositor on Windows-10, or if the reason is a different one, e.g., generally bad/noisy system timing or other display driver bugs: Screen('Preference','Visualdebuglevel', 6); If the compositor is at work, and thereby the root cause of timing problems, the window will turn …

-mario