Allocating a GID leads to a segfault, if winbindd has just started and is not fully set up. Volker has a patch, already :-)
This bug was referenced in samba master: 2e608468595d748f506a059811231c5572976157
Created attachment 16571 [details] Patch for 4.14 I believe this is a 4.14 thing only
As Samba 4.14 is now discontinued, I guess this bug can be closed.