TYPO3 Core

I have the following circumstances:
- one record with an IRRE field relating FAL files (see first screenshot)
- both relations are collapsed at the beginning

My click path:
- I opened the second relation to enter a certain image caption (see second screenshot)
- I collapsed the second and re-opened it
- the image caption field was gone
- I deactivated the check box and both occur instead of the gray one only (see third screenshot)

My work around:
- deactivating the check box so that both occur
- filling the white one with the content
- re-activating the check box (both disappear again)