Routing issue - overlapping subnets on two different L3 switches

Forgive the question, but I can not wrap my head around this.

On L3 switchA I have subnet 10.10.10.0/24 (no hosts beyond .240), whereas on switchB I have 10.10.10.248/29 (only 2 hosts placed here)

Network is running OSPF and the above SVIs are added to OSPF process, so that each switch has correct entries in its routing table (one entry with shorter prefix and one with longer one).

Problem is, even routing tables look good including less and more specific routes -- hosts from one subnet are unable to reach the other subnet.

At the same time either subnet's hosts are reachable from some other subnet laying outside of 10.10.10.0 range.

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Is it ARP issue? How can I make this work?

I know this design is far from desired, but I'd like to make it work for a few months before this overlap could be eliminated for good.

Thank you in advance.