Definitely try updating your Visual C++ 2015-2022 Redistributable (x64) if you run into this issue. I just had a failure to launch on an older laptop with a beta version of Sigil using Qt6.9.2. No error, just no launch. updating the redistributable fixed the problem. Damn Microsoft! These things are supposed to remain backward compatible (and they have for quite a long time), but it looks like something is starting to fall through the cracks. Sigil requires the x64 version.
Version 14.40.33816 was not good enough. The latest version of 14.44 restored all functionality. Spread the word!
https://learn.microsoft.com/en-us/cp...?view=msvc-170