When you keep press a button on IR controller, can you always see a solid (or quick flash) red light? If yes, normally the IR remote controller works.
Here I explain the difference between mBlock 4.0.4 and mBlock 3.4.11
The mBlock 4.0.4 is experimental version, to make the mBot works with IR controller, need choose the option “update the firmware for IR”.
The mBlock 3.4.11 is official version, to make mBot works with IR controller, need choose the option “Reset Default Porgram”-> “mBot” (not upgrade firmware).
For the problem, may I know do you choose the correct serial port (similar to /dev/tty.wchusbserial1410.) and correct Board (mBot -mCore) while Upgrade firmware for IR?
If yes, as Crackel mentioned, is there a little music (with the RGB LED switch different colors) after successfully uploaded the program?