Hi again,
Mumpi seems to have found a solution for the sequence problem: VS on Mac does not seem to like the spaces in the filenames when loading a sequence. I just renamed the sequence frames to names without spaces, i could load the sequence without any problem. At least for now. I will try to apply this method to the whole project and see if the "save and run" error will still be there.
You should always name your files with _underscores instead of spaces, to stay on the safe side! Same for names in the vs editor too (in case you need to access them via Lua script).

A typical good sequence name would be something like this:
protagonist_walk_west_000.png to
protagonist_walk_west_024.png. And putting them in separate folders or at least the different animation types is always a good idea as it makes it easier to find stuff quicker.