Messing up layout builder

Problem/Motivation

Block cannot be added to a layout builder region (two column section). I does show up under the available blocks, but cannot be 'saved´.
After saving the layout, the block appears however on the page, but not in the section where it was intended.
Trying to adjust the layout, I get the following message:

Message TypeError: Drupal\Core\Cache\CacheableMetadata::createFromRenderArray(): Argument #1 ($build) must be of type array, null given, called in /home/xxxx/domains/xxx/public_html/core/modules/layout_builder/src/EventSubscriber/BlockComponentRenderArray.php on line 111 in Drupal\Core\Cache\CacheableMetadata::createFromRenderArray() (line 149 of /home/greenhost/domains/lochemenergie.net/public_html/core/lib/Drupal/Core/Cache/CacheableMetadata.php)

Only solution is to unselect layout builder for the said content type, flush cache, and rebuild the layout again (obviously without toc block).

Steps to reproduce

Installed cron
D 9.5.8

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes