Storage Spaces stuck at "repairing 9%" and "starting repair"

I have a storage space with 8 disks, and 2 virtual disks.

One of the virtual disks started showing up as

"Warning: In Service"

If I ask to start repairing, it keeps at

"repairing 9%"

forever (I tested around 1 or 2 days) and the task details say

"starting repair"

At this point I cannot do anything with these disks, since if I try to remove a disk from the storage space, I am prevented by a message mentioning the fact that some virtual disks are not in a healthy state. Looking at event viewer I find some error messages, but I cannot understand if this is caused by a particular disk or something else.

- "Virtual Disk Service", Error, ID=9, "Unexpected provider failure. Restarting the service may fix the problem. Error code: 80004005@02000014"
- "VDS Dynamic Provider", Error, ID=40, "The remove plex operation failed to complete. status=C038003B "
- "Ntfs", Warning, ID=50, "{Delayed Write Failed} Windows was unable to save all the data for the file . The data has been lost. This error may be caused by a failure of your computer hardware or network connection. Please try to save this file elsewhere."
- "disk", Warning, ID=51, "An error was detected on device \Device\Harddisk16\DR16 during a paging operation."
- "disk", Warning, ID=51, "An error was detected on device \Device\Harddisk14\DR14 during a paging operation."

I have the same behavior regardless of wether the disk enclosures are directly connected to the Win2012r2 server, or if they are mounted via iSCSI on a linux server.

Any ideas on how I can get around this issue? Thanks