Hello, @Anielka OliverosWelcome to the Microsoft Q&A platform!
Based on your description, I want to confirm if you mean the shared account cannot applies to the approval process after applying the transfer rules .In order to solve your problem better, we have recreated the scenario and tested it based on the information you provided. After the test, the shared accounts could work for Approval Process as screenshot below.
If there are any misunderstanding, please feel free to contact me.
Also, If my reply is helpful to you, please mark it as the answer so that other users can refer to it. Thank you for your support and understanding.
Best,
Alex Zhang