Fail to add new thumbnail to database.

[minmax]

Is there a max thumbnail database size? I never had this issue but starting recently, the software fails to add new generated thumbnail to the database, which cause issue for putting files into different categories.

i tried making a new database by changing the folder location of the db in the settings and everything worked fine, then i reload my main db and the issue persists.
my db is quite large, over 40gb, is there a setting somewhere that limit its size?

edit: folders are not excluded

[user0]

there is no point in having a 40 GB thumbnail database

1. make backup of XnView.db
2. run Maintenance with first 5 checkboxes checked
    in Settings>Catalog>Maintenance