RSI closed value (because you use UPDATEONCLOSE) of 10′ o clock will remain the same until the next 5-min bars will close. So between that time all the 1-minute bar will use that previous closed value. It is only after 10h05 that the 1-minute timeframe will be able to use that new value.

Imagine that a year is the 5-min TF and a single day is the 1-min TF: My birthday is 2nd April, everyday after that I have the same age until another year has passed.