Adventure module tokens

[Randomisation]

I'm new to FGU. but have a fairly solid grasp on how it works. I'm running the Sunless Citadel module and have an issue with the enemy/NPC tokens. When an encounter starts I add the creatures to the combat tracker, and then drag the tokens from there onto the battlemap, and from my side it's all fine, however, my players are only seeing '?' tokens. The only way I have been able to solve this issue is by replacing the tokens using those from the Monsters Manual, which isn't the end of the world, but it is a tad irritating. Does anyone have any idea why this could be happening?

I'm hosting using FGU Ultimate. My players are using the demo version.

Apologies if this is the wrong place for this type of question.

[damned]

Hola Ransomisation - have one player clear their cache and reconnect?