If you’re using the “local db” function your database is only stored in a plain text file for sqlite.
When more than one instance (e.g. playout and separate database app, two playout instances on different PC or playout on PC and database app on a second one) are trying to access this file at the same time via windows only one of them can and then the file is then blocked for all others.
This will not happen when you’re using the db server because it will bundle the requests of all instances and only one connection is used to access the text file.