Bugs if adding too many clips

hi, i usually record 60x 10 seconds clips of my child playing football.

then in iMovie i create a new movie and simply select “select” on the top right in the gallery selection page so that it automatically selects and ands the clips of the day.

by doing so only a part (not sure how many, maybe 30) of movies are chronologically added from the oldest to the newest in the project. After that the order is not guaranteed.

same for audio: using theme soundtrack first part of the clips are correctly muted then you have double audio.

it seems iMovie has been tested only for a certain number of clips and after that there is a bug.