Welcome to the community.
https://community.enginedj.com/t/ability-to-shrink-expand-beat-grids/13703?u=mufasa
https://community.enginedj.com/t/improved-bpm-detection/16014?u=mufasa
https://community.enginedj.com/t/flexible-beat-grids/6433?u=mufasa
https://community.enginedj.com/t/bpm-adjust-in-grid-edit-mode/19301?u=mufasa
Give those feature requests a like 
You have to like the first post in the thread
You are experiencing a discrepancy between the imported BPM value and the actual value.
Eg the track may be 121.44 bpm but when saved it’s registered as 121 in the tags. Engine prime uses that 121 bpm value to create a beatgrid.
We actually requested this as a feature request as engine prime is still terrible when you use it Analyse bpm on its own.
You can override this by using the Reanalyze option in EP. You may get a better result ie 121.44 or a totally wild result Eg 90bpm.
https://community.enginedj.com/t/bpm-times-in-engine-prime/11357?u=mufasa
The other likely cause will be a non quantized track eg 70s, 80s music played by live musicians.