Grumpy_Mike:
The problem in the origional post was that the wrong type of Arduino was selected in the IDE.
This can happen if you are using rip off clones and you don’t know what type of real Arduino it is ripped off from.
Or just (like me) you did buy a genuine product but it’s not clear which settings to use!
I have a genuine Arduino Mega (easy), an Adafruit 5v Pro Trinket (not so easy) and a stand-alone ATTiny chip programmer (works completely different to how the website (and Customer support emails) says it does and I have to refer to the notes I made every flippin’ time...