Few Remote flows not deleted on DPNs after migration from internal to external VPN

Reproduction steps:
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1. Create 60 networks and 120 VMs(have 2 VMs in each network)
2. Make sure one VM is on DPN1 and one VM on VPN2
3. Create 60 routers and associate subnet to routers. Check all the flows and FIB till now no issues.
4. Associate 60 VPNs to 60 different Routers

In FIB all the internal VPN routes are properly converted to external VPN ,
in even in DPN all the new external VPN flows are populated properly.

But few existing internal VPN remote routes are not deleted.