Bug report already exists: Bug #118043. There is also one filed for transferring existing tables from another .odb containing decimal or numeric info: Bug #116893.
Have not seen any explainable pattern in this problem - gave up looking. I found only two methods to successfully move my data to Firebird Embedded - 1) via macro (real pain); 2) data transfer from Firefird Server.
This last method is noted in my answer in this post → Base: HSQLDB to Firebird migration for existing databases.
Have now discovered a third and easier method to resolve the problem. This method uses a text field as an interim in copying the data. While the process still requires a number of steps, there is nothing else to load or code to write (with the exception of an SQL statement). I have attached a document to explain the process simply because it includes many images to better explain it and therefore limiting the amount of necessary space in this answer:
Conversion document ----- FirebirdTableMigration.odt
To complete this, here is the Base file used in this process. This can be used to test the process if wanted.
Base file --------- TableMigration.odb
I am hoping this encourages others to now convert existing files. The fix noted for LO v6.2 is still not available as of this writing & nothing appears on the horizon as of yet. This is the critical piece missing in many cases - not being able to convert data correctly. And without data converted how is testing possible? Other problems exist but there are typically simple fixes to get around them. Not so for data conversion and many DB’s do use numeric or decimal types in tables.
Hopefully more people will now convert if only to test, as Firebird embedded is at least more advanced than the HSQLDB embedded now used.