there are complaints about it on the forum. What is the reason is though to know since most users are complaining then dropping out when it comes to investigating. Dropping out, as in ‘disappearing without even a good bye’. So what’s the matter really ? Duplicati as a true open source project attracts low resources users doing backups on consumer grade hardware, subject to all the failures of this kind of hardware: no ECC Ram, no server grade hard disks / SSD, no UPS, cobbled together NAS from (again) consumer hardware configured by Linux beginners.
There never was in years of complaints any kind of precise report to understand what could be the real problem. The main cause was that Duplicati is so slow to rebuild the database when something really nasty has happened on the backend (for whatever the reason, good or bad) that nobody cared to wait. Maybe this could change for the next release, though; see this thread: