A warm welcome to Dementia Support Forum
@anne mason.
Have you spoken to the manager and other staff about how your mum is when you’re not there? She may well be joining in with things, but forgetting that she is doing so. I also wonder if visiting every day is making her focus on you rather than engaging with staff and other residents. It sounds counterintuitive but maybe don’t visit for a week and see if that helps.
This is a very friendly and supportive place so I’m sure others will be along shortly twitch their ideas.