Syncing stuck. How to restart?

I’m using the Box app free version on my iPhone 11. One of my files has been stuck at syncing since yesterday. The funny thing is, that file has already been uploaded correctly, but it still says 1 file syncing and shows this filename. Also today I am trying to upload a bunch of short videos. For hours now they are all stuck at syncing - the two arrows going clockwise symbol. The symbol is rotating, but it doesn’t develop the yellow outline which shows the file is uploading and its progress. How can I cancel these uploads/syncing? I am unable to select and delete them from the ‘Sync Activity’