System:
Problem:
When using the "add existing" option for m2a fields there are no existing items showing (not only for one of the m2a fields, it´s for all)
I´m getting these errors (see screenshot)
I tried using a many to many field or one to many field and here the selection of existing items is working, but I don´t understand why...
I found the solution:
you need to check the "allow duplicates" field in the M2A field configuration to fix this error.