music random tracks greyed out (yet another one)

Hi

I use music to play, manage and synch my locally stored music collection...

All files are stored locally, present, and intact, on one harddisc.

Many files are greyed out when I open music.app on my laptop, indicating they were't uploaded.

This is clear enough.

I update the icloud library every time and often see that many files are being uploaded... but can it be that files don't get uploaded anymore if this was aborted in the first place?

I must say that the mac is on a really slow 4G connection, so this probably is one of the reasons.

BUT: Is there a way I can improve the upload-process? (Like, by upping music's connectivity-priority, or any other clever trick)?

Thank you so much!