Quartus Prime 18.1 Cygwin Error Win32 Error 487, Update Cygwin?

Qsys VHDL generation fails due to an issue with Nios II. Tracing this back leads to an executable within the Quartus installation of Cygwin that exists under ../quartus/bin64/Cygwin.

Running bin/bash.exe has mixed results with some executions failing. Attempting to run a command within the opened bash shell also has mixed results; either the command isn't found at all or it errors with Win32 error 487 (see below).

$ ls
bash: ls: command not found
 
$ ls
      2 [main] bash 6916 C:\intelFPGA\18.1\quartus\bin64\cygwin\bin\bash.exe: *** fatal error in forked process - fork: can't reserve memory for parent stack 0x640000 - 0x840000, (child has 0x800000 - 0xA00000), Win32 error 487
    797 [main] bash 6916 cygwin_exception::open_stackdumpfile: Dumping stack trace to bash.exe.stackdump
      1 [main] bash 11516 fork: child -1 - forked process 6916 died unexpectedly, retry 0, exit code 0x100, errno 11
bash: fork: retry: Resource temporarily unavailable
bash: ls: command not found

tl;dr: A seemingly ancient error has apparently resurfaced in my Quartus install.

What is the best fix for this issue? And considering this was a fresh install of Quartus Prime, I must admit this is not particularly encouraging.