Cubase PRO 9.5.41 on Windows 10 (1803 build 17134.376)
If you go to Inspector > Inserts
and click on Preset Management button and select Save FX Chain
If you create a New Folder in the Save FX Chain Preset window that displays
it will display the new folder twice immediately after creation but only one of the
two displayed is actually created.
in below example: New Folder TEST was created one time but displayed twice.