I had the same problem. I found a solution: dispense with imap. This can be in
two ways:
For work, I use getmail (and imap) to read messages from an Exchange server and
drop them in a maildir. Muchsync then coordinates those.
For personal mail, I just use muchsync to directly manipulate Doveco
I have just given muchsync a try and it synchronizes email and tags very
quickly. I am quite impressed by it!
Unfortunately, I have hit exactly the same problem that you describe: I
have to have a single machine that pulls in my email via offlineimap and
then sync to the others via muchsync. That
