@TrophicHater not part of the dev team, but I had a similar problem when I played Ismail 2.
I tried your issue in the scenario editor and I was able to replicate using Windows 10.
(For the DEV team these are my saved game and scenario files)
warrior monks w relics not all moving.aoe2scenario (984 Bytes)
rec.aoe2record (461.1 KB)
I placed 9 relics and warrior priests (just a random number not significant). one by one I commanded them to pick up the adjacent relic, and once they all had their relic, moved the group. Only three warrior priests moved for me.
I also experienced an issue while playing ismail 2 where I had groups of units (knights and war eles) not listening to move commands as a group, but would when tasked individually. I’d initially thought it possible it was an issue with the scenario, but now that seems unlikely. There seems to be some bug where a group of units can sometimes ignore move commands.
I’m linking our topics in each of our replies. Hopefully that’ll increase the likelihood that the devs, seeing one of our issues, will notice both and hopefully address both.