Ok, I'll save myself the hassle of providing additional information, since it's probably my graphics driver or the fact I dare to like shadows and nobody else can reproduce it anyway.
Permission dialogs seem broken in 1.26.2.9. This definitely seems to be the case for animation permission as well as attach permission -- clicking "yes" will not yield the desired result. Rolling back to 1.26.2.8 fixes the issue, so this is what I will do for now. Cross-checked several times.
Love, Lia.