You are confusing 2 things

1. After the 24 hours waiting period is up you have 1 hour to turn the setting on or you have to wait 24 hours again to have the opportunity to turn the setting on. This is not noted in any docs, I only heard this from another Lemmy thread where several ppl confirmed this happened to them.

2. Once you turn the setting on you can select if you want it turned on for 7 days or forever.