If you're matching the version of shim and shim-signed in the archive now and hitting this problem you have a different issue. It's notable that your manufacturer has a firmware option for boot order locking that is commonly causing similar behaviors. If you have enabled it, you may want to explore disabling it to try to help this issue.
@crosser:
If you're matching the version of shim and shim-signed in the archive now and hitting this problem you have a different issue. It's notable that your manufacturer has a firmware option for boot order locking that is commonly causing similar behaviors. If you have enabled it, you may want to explore disabling it to try to help this issue.