Is it just that the program hangs, or are you no longer able to upload programs to the Nano?
I've started to have problems uploading programs to clone Nanos with my Mac, after I upgraded to the new Arduino hardware drivers that now include the "Old Boot loader" option in the programmer menu. I even have one Nano where I cannot program the Nano anymore after a failed programming attempt.
However, on my Raspberry Pi, (except for the one was broken in the failed upload) I have no problems uploading programs to Nanos from my collection of cheap clones.
Don't know if this program upload issue-- with the new Arduino system upgrade-- is just limited to my laptop or affects other Mac or Windows users.
I'm going to program a Nano to act as an "ISP" and see if I can program a new boot loader into the currently not working one. Not sure if the cheep Nano clone boot loaders are (or even need to be) tweaked because they use different USB serial chips and possibility different CPU clock frequencies. (Based on the results I was getting with a recent program I wrote, I think some of my cheep clones may be running slower than the expected 16 Mhz, although I have not verified that yet.)
Tom, wb6b
