Hello Thank you for your question and reaching out. I can understand you are having query\issues related to Drive Mapping GPO.
- Disable fast startup using below command. Powercfg -h off
- Please try to edit your script and add some delay or pause after starting of second drive mapping.
- Please enable Configuration\Administrative Templates\System\Logon\Always wait for the network at computer startup and logon --If the reply is helpful, please Upvote and Accept as answer--