Error detected while processing function startify#insane_in_the_membrane[81]..<SNR>61_show_lists : line 35: E731: using Dictionary as a String E116: Invalid arguments for function append

Hello,
Sorry to bring this up again, but when trying to go back to Startify from an open nvim buffer (:Startify) I get this error:

Error detected while processing function startify#insane_in_the_membrane[81]..61_show_lists : line 35: E731: using Dictionary as a String E116: Invalid arguments for function append

I have checked it is caused by the added funcref/bookmarks.
Startify opens initially fine from the command line though, just throws this error if you try to go back to it with :Startify.
Any ideas I should try?
Thanks again for your help and plugin.
Mike

Reproduce the problem by opening Startify from an existing Neovim buffer with :Startify while funcref or bookmark entries are configured. Start at startify#insane_in_the_membrane and the reported 61_show_lists line 35, then compare the initial launch with the return path. Done means :Startify opens without the E731 or E116 errors.

Written by the indexing model from the issue text.