thank you for the prompt reply.
just checked it again, in my case, Adblock can't keep the "Filter Subscriptions" if the checkbox "Cookies and saved website data" is checked.
I checked all the checkboxes excluding "cookies", and after the "close/open" operation, all subscriptions were on their place (remained).
so, maybe the problem is on the "Cookies and..." checkbox side.
Windows 10 Anniversary Update Version 1607 build 14393.351
Microsoft Edge 38.14393.0.0
Microsoft EdgeHTML 14.14393