Ah, so you are not using the Legacy method of scheduling, but rather the Microsoft 365 version.
The issue is still the same and the workaround is the same.
3CX doesn't know about the reoccurring portion, that's all happening outside of 3CX. So when in 3CX you schedule a meeting for Jan 15th, then in 365 you edit to reoccur every week, all 3CX knows about is the 15th, not the 22nd, etc. So after the 15th, it gets deleted from 3CX.
The workaround is to set the meeting date in 3CX to a long time in the future - say Jan 1st 2025. Then hit the button that brings you to 365, edit the meeting to be Jan 15th 2023, occurring every week. The link and PIN will work until Jan 1st 2025 this way.
Does that clear things up for you?