Curious about that, I think I can count these events on one finger a year (and maybe the absence of direct `git push --tags --force`). For me it's some strange state where creating a branch from a remote doesn't linked the two. That's about it.
Usually :
- reset - rebase - fetch / pull / push - cherry pick - stash
and then magit-blame, git-timemachine etc.. all work smoothly
But we all have our own usage, what did you try that made magit get stuck ?