Squeak when tonguing reed

I recently changed reeds on advice of my instructor. The new reed works week except for a nagging issue. When I play the lower register notes I squeak if I tongue the reed, but not, if I slur from note to note. I’ve tried adjusting my embouchure, compressing my diaphragm, adjusting my jaw and lips. Nothing seems to be a permanent fix. When I change things, the squeak may disappear for a couple of notes and then bam, the squeak is back.

Has anybody solved this? If so, what was your fix?

Thanks!