Disabling songs for RS1 Compatibility DLC under the Song Packs tab generates an error and corrupts the psarc file

[KwasimodoZA]

Actions:
Click song packs tab
Choose RS1 compatibility DLC from the song packs drop drop down list
Select any song
Click disable
Click save

After a few seconds an error dialog box appears:
Application.ThreadException:
Object reference not set to an instance of an object.
Please send us the debug.log file if you need help.

Here is the log file:
debug.log

rs1compatibilitydlc_p.psarc is also 0kb after clicking save