If you look at a RITM record, when you open it, the REQ value is being cleared upon loading (thankfully this is not being saved).
The issue occurs due to custom Ui policy on that specific catalog item.
g_form.clearValue('request') was used.
As per "applies to" in the UI policy record the details will be listed as per the below documentation.
Applies to : Select the type of item this UI policy applies to:
A Catalog Item: enables the Catalog item field.
A Variable Set: enables the Variable set field.
Catalog Item or Variable Set Select the catalog item or a variable set this UI policy applies to. The field name and options available depend on the Applies to selection.
Now, in this case, an advanced script was used in which it is pointing to the name "request" which is the same name as of field and variable, which is not recommended.
Fields name should not be used for creating the variable.