copying element into container not working after update to 3.1.x

[ttg-barbreit]

we have an typo3 instance v12.4.x that uses container, content-defender and mask.

Versions (all latest):

• container 3.1.3
• content-defender 3.5.2
• mask 9.0.7

after the update to container version 3.1. both admins and editors now get an "The record xxx couldn't be saved due to disallowed value(s)." error, when trying to copy an allowed element into a container.

This error originally comes from content-defender, but rolling back to container version 3.0 does not cause this error, therefore this is hopefully the correct repo for this issue.

setup:

• container with a single column that allows the mask element / CType "mask_bild"
• adding a new element of that type to the container works as expected
• when trying to copy the element into another container, where the CType is also allowed and therefore should be able to be copied, the error gets thrown
• the container has no disallowed CTypes
• the backend_layout DOES has disallowed CTypes, including "mask_ncebild", but since the editor is trying to copy into the container, not directly into the page / backend-layout column this should not affect the action

both creating a new element in the container and moving the element into it, is working as expected, only copying an existing element seems to be the issue.

for now we have reverted back to version 3.0