You seem to have some invalid options in the theme manager, I see errors in the log:
[2022-03-30 10:50:13.149] LOAD manager themeManager
[2022-03-30 10:52:07.048] error: argument `$color` of `red($color)` must be a color
[2022-03-30 10:52:07.048] error line: 37
[2022-03-30 10:52:07.058] Unhandled rejection Error: argument `$color` of `red($color)` must be a color
at C:\Users\jed\AppData\Local\Wappler\resources\app\node_modules\node-sass\lib\index.js:291:26
[2022-03-30 10:52:59.104] error: argument `$color` of `red($color)` must be a color
[2022-03-30 10:52:59.104] error line: 37
[2022-03-30 10:52:59.111] Unhandled rejection Error: argument `$color` of `red($color)` must be a color
at C:\Users\jed\AppData\Local\Wappler\resources\app\node_modules\node-sass\lib\index.js:291:26
You should get an alert with the error as well