Was there a resolution to this issue? I installed Ubuntu 20.04LTS to run on an arcade cabinet. I tried several other flavors of Linux but most did not like my hardware, or I did not like them. I settled on Ubuntu 20.04 and installed MAME from apt and I think it is 0.220. I want to install QMC2 because everyone says it is one of the best out there but it seems it is abandoned. Are there any instructions on how to set it up and where to get an updated version of it?
As far as I know, the author of QMC has been dealing with health issues and hasn't had time to work on QMC for a few years. I wouldn't expect this to be fixed until he shows up again regularly, assuming his life allows such.