submodule causes install error with vim-plugged

[flwyd]

Using https://github.com/junegunn/vim-plug I have this plugin installed via Plug 'editorconfig/editorconfig-vim'
When I run :PlugUpgrade I get the following error:

x editorconfig-vim:
    remote: Enumerating objects: 122, done.        
    remote: Counting objects: 100% (106/106), done.        
    remote: Compressing objects: 100% (20/20), done.        
    remote: Total 29 (delta 19), reused 13 (delta 7), pack-reused 0        
    From https://github.com/editorconfig/editorconfig-vim
       c718cef..2ad3d78  master     -> origin/master
    Fetching submodule tests/core/tests
    From https://github.com/editorconfig/editorconfig-core-test
       48610d4..761fdd3  master     -> origin/master
    error: Server does not allow request for unadvertised object 05653f1e10d7508d24c9df9b0f2bb6b6f605d347

Should https://github.com/editorconfig/editorconfig-core-test have its permissions changed?
If not, is there a way to avoid this error when checking out the plugin repo?

[cxw42]

That is a strange one - the error does not appear to be permissions-related. What OS version, Vim version, vim-plug version? Console or graphical?

Despite this error, the plug-in should still work fine. Does it?