I recently built and installed mpc-qt from Arch aur (AUR (en) - mpc-qt). However, the built binary did not show anything but an entire black window, which is not seen in other Arch distros. Editing makepkg.conf to Arch’s default parameters did not change the symptom.
I guess optimizations implemented in some qt dependencies would cause this symptom. I am wondering whether anyone else encountered and/or resolved this issue. Certainly, we have a suboptimal solution, using pre-built binaries, and this issue may not be a serious problem to a user.