Looks like you have deleted the whole track instead of just a segment (wrong button).
We’ve changed interface a bit to be clearer on this.
Lost track can be re-uploaded from the phone.
Currently, segment deletion does NOT lead to deletion of the corresponding track part. Track can only be deleted as a whole.
A segment just “highlights” an interesting part of a track and makes it playable.
In your case just narrow the segment so it doesn’t contain irrelevant parts.