its been my experience that each time Ive had a ph issues, that late in bud......... it did seriously affect my resin production, and there was very little smell to the plants, I grow mainly the same strains over & over so I know the diference

I have a meter like yours, I have a chemy Ph test kit, a $50 PH pen & a PH truncheon that cost $160.00 I can tell you those meters you have arent accurate, & cause you grief like your going thru now.
I wont even rely on my ph truncheon the chemy test is always needed as a backup test kit, when the plants are crying

look into a soil runoff test as posted above