This information is based upon LO v 5.2.3.3 on Mint 18 using an embedded DB.
First created simple table:
Note that entry is required & length remains at 1.
Entered some data:
No problem.
Add another BOOL field:
Cannot add with Entry required = Yes
because existing records would have NULL entry. Set Entry required = No
and following is table:
Either modify records directly or through SQL update. Then back to modify table field to Entry required = Yes
and some table entries:
The field length does show 0 but can now input records without problems.
The error stated indicates some field entered incorrectly (truncated). You don’t state whether data was entered prior (not likely because of error indicated above) to this BOOL field being added. The problem could possibly be in the date format (or type) chosen and what is being entered.