Maybe go the opposite of what your trying.... completely ignore him for 1.5 weeks .... maybe 1-2 pellets only a day, and that’s it. Do not make eye contact, do not gravel vac or change water, just let him claim his territory
I had to ignore my trimac this way ( only did gravel vac a every two weeks) and now he not only glass hangs again, but also eats anything I throw in the tank. This might be anecdotal because I also upgraded his tank, but if what you're doing isn’t working, you may try the complete opposite approach
Well mine did get the tank upgrade from 75 to 90, lol. I know, not a great upgrade but the taller tank did make him feel a lot more comfortable. If I ignore him... I will likely just rehome him.