upekkha is not a feeling but a perception ( sañña)… (this passage seems to call it upekkhāvedaniyā? i don’t think that’s common…)
neutral feeling in Buddhism is just any feeling that’s not clearly dukkha nor sukha
the mind tainted with ignorance feels a “neutral” feeling and reacts with boredom, distraction, basically delusion (and habitual greed/lust in the case of positive feeling, and aversion in the case of negative)
upekkha is neutral-ish, yes, but really it is something much more in the suttas; it is a result of wisdom. upekkha apparently comes from ikh root with upa- prefix, meaning something like over-seeing. to me, there is an element of distance embedded in the idea, one is seeing from afar, the bird’s eye view, if you will. this is in-line with the disassociation/de-identification inherent in the wisdom of the suttas. upekkhā is going beyond desire and aversion in regard to the world, and beyond even the positive feelings of meditative experience. really it is quite exalted in the EBT’s: take for instance it’s place at the pinnacle of the brahmavihāras, the pinnacle of the 4 jhānas, the pinnacle of the 7 awakening factors.
jmo. maybe you can come up with examples?