Source code is not displayed on dbt docs page with dbt-core=1.4.5, dbt-utils:1.0.0 version when hosted on app engine

The problem I’m having:
After upgrading the dbt vesrion from 1.0.0 to 1.4.5 , Source code is not displayed on dbt docs page when hosted on app engine whereas it is displayed with dbt docs serve command.

What I’ve already tried:
1.dbt version 1.2.5 with dbt utils 0.8.0 is working on app engine.
2.dbt version 1.3.3 with dbt utils 1.0.0 is not working on app engine.
3.dbt version 1.3.3 with dbt utils 0.8.0 is not working on app engine.
4.Any version is working using dbt docs serve command

Please suggest.