You’re welcome @gary. 
Btw, if you hadn’t yet seen, I did find the below post where @Norm discusses needing to create a temp working area when using project assets on external drives because of a quirk in MacOS.
I did verify that this temp area usage does occur when using my external drives with blocs project files. FWIW, I’m thinking it’s probably simpler/safer (using the current version of Blocs) to copy any external drive project files into an internal drive user area of the new computer, make the blocs edits, then copy them back to the external drive when done. That way the Blocs app is running more in it’s default way when using projects assets instead of needing the copy to the temp area.
Have a good day!
Paul