Rel10.1 - Reg - Upstream - Unable to create X-Site / At Site Meeting Document

1. Login to Upstream SR as PP or PP/CS or ES
2. filter and select a material
3. Click on 'X-Site / At Site Meeting Document' button from PIR

Expected: X-Site / At Site Meeting Document page should be loaded and user should be able to create X-Site / At Site Meeting Document.

Actual: Page is not loading and spinning for long time. after sometime we are getting timeout error

if we navigate to any other page or app, then warning msg to save the meeting is displayed. but the screen is showing as still loading

refer attached snapshots