I switched to texlive 2018 yesterday.
My Build-Environment: Win64, Texstudio, latexmk, lualatex, biber.
I tried to compile a test document - it worked fined using my old TL-17 and the new TL-18 installation.
Today I updated the TL-18 installation (using:
tlmgr update --all). Now latexmk does not work anymore - I guess it crashes. I guess, because I don't get any output and I don't know how to further debug the problem:
Calling latexmk manually (e.g.
latexmk --help) reports nothing: no help, no error message is printed. latexmk delivered with TL-17 still works fine - see this screenshot: