In a table in a base form, it is no longer possible to enter a new record. I first noticed this in Manjaro, but it has since shown up in Fedora, and now Mint. With it being across several distros, all differently based, it is definitely a LO bug, and not specific to a single distro or line.
This only seems to occur with external DBs and JDBC. Self-contained appear unaffected.
All external DBs are being opened in read-only mode. There seems no way to change this behaviour.
SOLUTION! It appears MariaDB can not handle importing .sql files with both tables and views. Dump (from the ORIGINAL DB) tables to one .sql file, and views to another. Import them separately, Tables first. If you don't, your data will be there, but none of the constraints or keys. Without those, the data can be viewed, but not modified (Read-Only). It took a fair amount of fiddling to figure this out, so I'm reporting it here, even though it turned out not to be a LO issue after all. Fortunately, i still had access to the original DB. It would probably be possible to weed out the offending views with kate/gedit, and transfer them into their own .sql file, but it might be more effort than was pretty, so I wouldn't try it unless you've already destroyed the original DB. Even then, use a COPY. This is also the solution for #100840.
*** Bug 100840 has been marked as a duplicate of this bug. ***
Thanks for the analysis! If you suspect this is an issue with MariaDB, have you reported it there?
Yep, report here: https://jira.mariadb.org/secure/Dashboard.jspa