Thanks good tip.  Remove HA / remove FTDs.  Log into FTDs cli  - commands: configure high-availability disable (both FTDs) , (both FTDs:) show manager ... if manager is set:  config manager delete followed by config manager add (FMC IP) x.x.x.x KEY (...

Have a tac case open for same issue Have you resolved?

Erwin, Were you able to determine this issue?  I'm having the same....

Thanks for this post.  Same issue - same resolution as posted