MBS plugin signature encoding problem

Hello, Im currently trying to create integrations to Netsuite (via REST api).
For authentication oAuth 1.0 is used.
Ive had success testing with Postman but now Im struggling to authenticate with MBS plugin in Filemaker.

The problem Im facing is with signature encoding.
In postman the signatures always have "%2" somewhere in the signature and "%3D" at the end of the signature.
With MBS plugin the signature has no "%2" inside but it does have "%3D" at the end.
Is there a setting/configuration that Im missing?

Ill gladly provide more information if needed.
Any help would be appreciated.

Welcome to the soup!

@MonkeybreadSoftware surely an provide help.

Well, the description doesn't ring a bell.

Maybe the URL encoding is different?

What is the signature in MBS vs. postman?