Hi,
Sometimes I deviate a bit from the Garmin coach plan and on some occasions this messes up the pace diagram in Garmin Connect.
On one occasion I just kept running at a faster pace after I finished the planned distance/time. When I checked the pace diagram afterwards it looked like this
The target pace line is wrong
Another time I had to do some interval training (1min run with 3min rest) and decided to add two intervals during cool down.
This messed up the target pace line, putting the high pace onto the rest period.