If you have not already applied the 7.0.1 update, please do so. A bug that caused a problem like what you're describing is fixed in this update. In most cases, affected multicam sequences are corrected by the fix, but some users have reported that the damage was not undone.
Please clarify. After applying the update, did you create a new multicam sequence, record at least two passes of edits, close and reopen the project, and find that the each edit reverts to the start of the clip? Or are you reporting that the multicam sequence that you edited in 7.0 was not fixed by the update?