I use Declarative Pipeline and Multibranch pipeline job.Every time after restarting Jenkins due to plugin upgrade,the hidden stage 'Declarative: Checkout SCM' in Declarative Pipeline will not be executed and will be skipped.As a result, new changes can not be fetched from the git repository.But when I clicked 'Scan Multibranch Pipeline Now' manually, it fetched changes.

In the attachment screenshot 'first', build worked fine and General SCM in it. In the attachment screenshot 'second', General SCM was lost and it did not fetch new changes.