Strange Bug: group by "Edition" broken in 5.2a Beta 5

Trying to group the - filtered - library per edition (expected result: two groups, one "Logos", one "User created" ) gives the book in two groups, one "personalbook" (sic!) and one "logos" (sic!).

The books are not grouped, in fact the books in first group are copied from second, the functionality is completely broken.

Note: filtering by edition:u (not: p) still works.