Uncheck 'Compile in a separate Assembly'

Hello Creatio Community,

I'm trying to uncheck for some specific packages 'Compile in a separate Assembly'.

But checkbox is not clickable for every of my custom packages.

Anyone any ideas ?

I'm using Version 7.18.4.1532 BankSales_BankCustomerJourney_Lending_Marketing_Softkey_MSSQL

Thanks