FWIW
A wise man once told me," If what you are doing ain't workin', try something else".
I dont see you specify where you tried (at least) a 10% less load than max. All reloading manuals advise starting low and working your way up to max, unless you have indications, such as you have, to stop or back off a tad. There is nothing wrong with shooting a load less than max if it makes your gun work.
Start with a lower load, if OK, increase the charge a bit. Work your way up like this until you get 'signs' than you have reached your limit with these components. Then back it off a tad and see if your function is OK again. If it is, note it in your records and sit down and get serious about shooting groups and forget about it 'not being a maximum load'.
If it shoots good groups you can sit back and smile (
) and the targets or critters arent likely to know the difference.