BGP next hop unreachable

I have unusual situation where 1 mikrotik (R0) peering with 2 mikrotik routers (all in same subnet). And lets say that 1st mikrotik has IP 10.10.3.21/25 and two peers are R1 10.10.3.1/25 and R2 10.10.3.2/25

There are many routes exchanged between them and what is issue that for some routes on R0, next hop is reachable but for some it is unreachable?

https://imgur.com/1S0I1Dx