Attachment information is stored in bug_file table including folder location. Column 'folder'.
The folder information is based on input from the project settings, the project table, column 'file_path'.
all good here.

Where it goes wrong is when changing the folder location within the (same) project.
When changing the folder within project settings;
1) new attachments will be from now on stored within the new location. --> good
2) new folder location is also stored within bug_file table. --> good
3) bet when i'm trying to open a previous attachment, located in the previous location, the attachment can't be found. --> Wrong!

The correct location is stored within the bug_file table.
Why is the project table 'file_path' information used instead of the 'folder' information from the bug_file table?

Reason of my question;
I have a project with over 10.000 attachments.
Due to FTP limitations, which can handle only maximum of 10.000 files within a folder, i need to change folder from time to time.
I don't want any attachment folder to go over the 10.000 files. That's why i want to change the folder location from time to time.