Back when I first started attempting to play to a metronome, I found my biggest problem was playing too fast.
I had to slow down to 1/10 speed in order to maintain a steady tempo. I slowly ratcheted up the tempo until things fell apart, and backed it off until I could keep the tempo solid.
Over time, it was EXACTLY like all the other 10 million fundamental things guitarists need to learn. Conscious repetition to embed it permanently into muscle memory.
I've watched guitarists struggling with a tempo, say 120 bpm. I suggest slowing down the tempo. They set it to 100.
And they were surprised it didn't help...