My son won’t see me

I have a 19 year son with severe autism and intellectual disability. He lives in a group home. Suddenly he won’t see me. He  is  stable in his group home and day program. On the surface nothing has changed. We see him once a week in s park because he gets agitated if we see him at home. When i go to the park he shouts very loudly “mummy gone”. He has few words but it is clear he doesn’t want me there. He’s ok with his Dad. When he is upset it is v difficult to know why. I am devastated as it’s the only time I see him. I’ve had professional advice but his wish not to see me is not changing (thus far). He was v close to me before he moved out but that was several years ago. I feel i have lost a relationship with him. I wonder has anyone experienced this before and how they approached it . Thank you. First time posting so not sure where it will land.