As another line of defense, I use an internet backup service (Backblaze) and a local backup software (SyncBack) that backs up my computer to local external hard drives. (And also because I have some big files in my Box folder that are not synched because of the size limit of 250 MB on free accounts).
Checking on the backups, I noticed the Box folder is not picked up or seen by those services. I checked and there's no filter setting that excludes the Box folder. Not sure what's going on. Any insight appreciated!