Field widget settings not editable for block

For some reason, changes to the field widget settings, like "Initial Page Length" or "Enable searching" are not saved on edit when using this field in a custom block.

## Steps to reproduce
- Add a CSV field to a custom block type
- Create a block with this new type
- Upload a CSV file and change some settings, like "Initial Page Length"
- Save
- Edit the block, make changes to the those settings and Save again.
- The changes to the settings are not saved.

The field works as expected when used for a node, but not a custom block.

Could this be supported somehow? I'm not sure why a field widget would need to be different for a block entity.