Mom keeps losing call button necklace

This is my first time posting here. We moved our mother into assisted living just over a year ago as she was experiencing cognitive decline. While the adjustment has been difficult recently she’s become paranoid about her stuff going missing, I understand this is part of dementia. First it was her personal belongings like her pictures and figurines but this month she has started hiding her keys to her suite and her call button necklace. Original set we cannot find. We’ve checked her room three times and haven’t found it. We got replacements and paid $300 for the replacement call button. Last week the replacements went missing. My sibling found them hidden away. Now again this week they have been hidden again. We don’t live close by and enabling travels for work and I don’t love that close and don’t drive. I’ve noticed a pattern that it happens on cleaning days only. All week she has them and then on cleaning days they disappear again. We don’t want to keep paying $300 every week to replace it. Our mother didn’t leave the building so the original and now replacement are somewhere in her room or the building. Putting a tracker on it is one idea but it would still require us to go there and help look for it. Does anyone have any ideas of what else we can do? We’re at the point where we may have to not have one but they are required where she lives and we don’t want to move her to a new facility as it has taken this long for our mother to just barely adjust. The staff are great and she has made a friend so we really want to keep her here. I will meet with the care team and see what they say but so far they have just said to get a tracker. Any tips are greatly appreciated. Thank you.