This has definitely worked in the past for me, has support for it been removed recently? The same settings work fine when specified at boot time.
The tvservice and support for video mode switching are not part of RetroPie, but a Raspbian/Kernel+firmware feature - it was certainly not removed in RetroPie. What does 'in the past' mean ? 1 year, 1 week, etc. , before doing any kernel/firmware updates, using a certain RetroPie version maybe ?
What version of RetroPie are you running (specifically) and how it was installed ? Can you post your config.txt configuration file ?