[backport] fix unfulfilled callbacks (#1297 and #1305)

[vhakulinen]

Backport #1297 and #1305 to v11.

Requires another commit from #1285 to apply the commit semi cleanly.

~Haven't tested this yet, but throwing this here for others to see.~ Seems to work, but have to wait for user feedback (facing similar challenges with testing as reported in #1297)

Update: I haven't been able to confirm that #1297 alone fixes the issues we're seeing, but I managed to notice a situation which #1305 fixes nicely.

Each commit includes information where the patch came from to make review easier.