Trying to create a special rhythm track

Example of type of rhythm track I’m trying to create:

57.7 bpm for 6 minutes, then 59 bpm for 6 minutes starting at 6:01 into the track, then 60 bpm for 11:58 starting at 12:02 int the track.
So far I’m only saving the initial 6 minutes. The rest disappears or was never recorded.

  1. Generate the first 6 mins,

  2. then press the “End” key to move the cursor to the end of the track (or: “Select menu > Region > Cursor to Track End”)

3)then generate the next 6 mins