Maven 10 boss fight invite drops

After finishing the Lex Ejoris 10 boss fight another 10 boss Lex Ejoris invite dropped. Now I'm not able to use it until I have Maven witness 10 more boss fights in that region.
Does this mean that when I do kill another 10 bosses with her witnessing that the invite will not drop automatically? If the invite does drop automatically, what's the point of the random invite that dropped for me? Is it in case I fail a 10 boss encounter I can try again? Does the encounter reset if you fail and I have to gather 10 more bosses?
So far I have not failed at a Maven regular boss encounter so I'm not sure what happens to your progress.

The first 10 boss invitation while you do the Maven questline for a region is a guaranteed drop. Everything after that is RNG. You can collect ten bosses and fail the fight without dropping another invitation and failing the fight means you'll have to start all over again. RNG also means that you might drop invitations from other regions or even from uncharted realms.

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Baharoth15 wrote:

The first 10 boss invitation while you do the Maven questline for a region is a guaranteed drop. Everything after that is RNG. You can collect ten bosses and fail the fight without dropping another invitation and failing the fight means you'll have to start all over again. RNG also means that you might drop invitations from other regions or even from uncharted realms.

Ahh gotcha. Thats what I was thinking was going on. Thanks for the explanation.