Ollie being crazy over something in the yard

So I started about the nightly routine of rounding up Oliver to get him into my room so we can get to bed (He gets shut in my room with me at night so he stays out of trouble and off my parents' bed - mom's a little allergic)... I go downstairs and he's in the living room but darts towards the kitchen as I come down... I'm thinking he's angry cuz I'm late getting him his wet food and that he's headed for the fridge to beg but no, he darts to the open sliding screen door (my dad was still awake so we hadn't shut the glass one and locked it yet)... seems he's fixated on something in the yard... I put on the flood lights and went out to look but I don't see or smell anything unusual (I know his senses are more heightened though).... so I get his food out and grab a snack for myself and sign "food" to him (which usually brings him running to follow me upstairs) and he starts towards me, but doesn't follow me up... so I put everything upstairs and go to get him and he's back at the door... I pick him up to take him upstairs (usually not a problem) but he gets all wiggle wormy and protests a lot... I got him upstairs though and shut the door but he's been at my window (overlooking the yard)...

He's just way out of sorts and I don't know why... it's not about to storm or anything and as far as we've seen this season, there are no stray/feral cats around

I've sprayed some feliway to try to calm him, but nothing yet... he just went potty, but still out of sorts and begging to get out of my room and hasn't even looked at his wet food which is way weird!

I think I'm just going to shut my windows and throw on the AC... I'm warm as it is and when he gets in bed with me, I know I'll sweat bullets - hopefully that will mask whatever it is that's outside that's bothering him

So basically.... any ideas/thoughts on this oddness? He had time outside on his harness/lead this evening and didn't act strange - just ate grass, watched bugs and put all the birds in a tizzy... Guess I'll try offering a few cookies now too

So here it is 5am and after a couple hours of being ok, Oliver's going crazy in my room again... I got the feliway diffuser plugged in now

I even just let my black lab out in the yard (unstoppable nose) and she didn't hit on a single thing... so idk if Oliver saw something sometime last night and even though it's gone, he's still reacting...? I had to leave a note out in the hall to be very careful opening doors since Ollie's freaking - I don't want him darting outside

A cats eyes and ears are as sharp as their nose. It could have been the shadow of a flying bug or bat and even the scurrying of a mouse or lizard. Probably they're gone but Oliver just wants to make sure.