Photo memories not created automatically

Hi!

a while ago (a year+) my phone stopped creating memories automatically. It used to create them regularly, for individual days, periods, people, etc. Then, it suddenly stopped creating them. I can still manually create memories, but the photo app simply doesn’t create them automatically anymore, although I still take pictures just as regularly as before. Switching devices hasn't changed this odd behavior and in fact I cannot recall having made any change to trigger this. When trying to find a solution to this issue, I kept running into threads where people ask how to turn memories off - but in fact I quite like that function, so I’d appreciate if someone could advise me how to turn it back on. By the way: the old memories are still available, and some of them are still being updated, e.g. ones showing pictures of people, if those memories had been created long ago. It’s just that new topics/themes (such as for a vacation) are not being created any longer.

Thanks for any advice!