*** [OMEMO] Unable to build any sessions, the message was not sent (Last in Protected MUC Room)

[Neustradamus]

Dear @psi-im team, @psi-plus team, @Ri0n, @Vitozz, @tehnick,

If the last person wants to send an OMEMO message, there is always:
*** [OMEMO] Unable to build any sessions, the message was not sent

Linked to:

• *** [OMEMO] Unable to build any sessions, the message was not sent (Myself message does not work) | Identical chat tab | Identical device #49
• [OMEMO] Protected MUC Room problem, if alone -> OMEMO is forcing: *** [OMEMO] Unable to build any sessions, the message was not sent #57
• *** [OMEMO] Unable to build any sessions, the message was not sent (First in Protected MUC Room) #121

cc: @stigger.