Merwinsson

I can answer this question.  But you won't like the answer.
Everything REQUIRES a volume that is capable of JOURNALING in order to work its magic.  The volume provided by DRIVEPOOL does not support that.  I know, bummer, but these are the facts.  I've already gone over this before a couple of years ago and there should already be a forum thread that talks about this situation.
Now for a small bit of good news...you CAN get Everything to work with a DRIVEPOOL volume BUT it works slower.  You have to fiddle with the settings and ADD ALL DRIVEPOOL drives to a special list in Everything.  Do that, and then Everything will work, BUT, as I said, because Everything uses the JOURNALING info to work its high speed magic, you won't get the blazing speed you've come to expect...but at least the program will function.
Look at the following screencap.  You have to add any DRIVEPOOL drive you want to index as a special INDEXED FOLDER (like my S:\ drive, which is the root of my filesystem on my DRIVEPOOL volume).

I think I can help you with this.
I also added 2 disks to my pool recently and had a similar issue.  Well, it wasn't quite the same in that I could see (from the UI) that the balancer was running but it never seemed to get anywhere, even after a day.  So this is what I did.  I downloaded and enabled the "Disk Space Equalizer" plugin, then DISABLED all other plugins other than "Stable Bit Scanner".  Finally, I made sure "Automatic Balancing / Balance Immediately" was checked.  Off it went and 1 day later all my drives were rebalanced.
Another thing I noticed that may have hung things up was that I had some pretty odd permissions on some files and they caused the background balancer to spit out "Access Denied" errors.  I thought that was strange because I thought DrivePool's core processes would have all the permissions they needed to do their work.  But it turns out I had to fixup said permissions to get things to work.
Hope this helps.