Sorry, yes, was just adding some more helpful detail. Here's an example:
The original project is project id 231231
The copy I just made on a different account is 2419592
Both are on Ubuntu 16.04.
The specific problematic package is stringi - on the copy, I get this error message:
Error: package or namespace load failed for ‘stringi’ in dyn.load(file, DLLpath = DLLpath, ...):
unable to load shared object '/home/rstudio-user/R/x86_64-pc-linux-gnu-library/4.0/stringi/libs/stringi.so':
libicui18n.so.55: cannot open shared object file: No such file or directory
But it works fine on the original. The file is there on the copy, too - I can find it through the Terminal. Maybe permissions not copying, or something... either installing the package again on the copy or upgrading it to Ubuntu 20.04 (which I guess reinstalls the package - ah, a lightbulb just went on) makes it work.
this isn't project specific, as I've had the same problem on multiple projects. Making copies worked fine last week.