Constant error message "Cannot open backup file .....tib while consolidating backup

Hi,
when my daily incremental backup plan (auto-cleanup enabled) is almost done it starts consolidating and then always
prompts me for missing backup files (.tib).

From the filename I get prompted I can tell that it relates to a no longer existing backup plan, that I have deleted from the List of True Image backup plans.
No files or any settings exists for that particular .tib file

I already deleted that backup plan that prompts me with a missing .tib file however that didn't help.

Appreciate any help on how to troubleshoot.

Thanks
Bodo