hashmode is independent from hcxdumptool. You can use hcxpcangtool on that pcapng files to convert them.
I'm still hunting for that kernel bug, like other coders, too:
https://bugzilla.kernel.org/buglist.cgi?...%2Fslub%20
https://bugzilla.redhat.com/show_bug.cgi?id=1743043
https://bugzilla.redhat.com/show_bug.cgi?id=1777601
https://lists.gt.net/linux/kernel/3390507
I'm still hunting for that kernel bug, like other coders, too:
https://bugzilla.kernel.org/buglist.cgi?...%2Fslub%20
https://bugzilla.redhat.com/show_bug.cgi?id=1743043
https://bugzilla.redhat.com/show_bug.cgi?id=1777601
https://lists.gt.net/linux/kernel/3390507