Overactive colorization problem

[Churys]

I recently upgraded to Gimp 2.10.8, coming from 2.6 (or 2.8, unsure). Ever since then, several functions pertaining to the different color modes do not work right. If I use overlay, lighten, darken, hue, etc, empty area will be filled as if I were using a regular mode brush, while the solid areas experience the effect. When using tablet, pen pressure sensitivity of the pen worked only once, during the session I had activated it; in later session it is switched to active but doesn't work.

This all worked without any problems on the previous version. Might this be a problem of computer settings, or there anything else I can do to fix it?