I have an issue thats similar with my macbook pro mid 2014 15” it does not appear to do an SMC reset. I also have sound issue where the speakers start the bong at start up but the bong then goes as if someone has muted the speaker there is nothing wrong with the speakers, they just work sometimes. However i have to use this laptop now with my 27” apple monitor. Thought it could be the mini display port or the usb socket causing the issue, but i have no idea. I also feel like apple does not help with older models. I think that the update to Big Sur had seriously screwed it, however running latest patch and it still does not work. I feel like leaving this outside , and then reporting stolen.