IR ESA after UC claim

I may be over thinking this but this scenario doesn’t seem to make sense. Cl was migrated from IB to CB ESA and IR ESA some while ago and has just had a payment of arrears due because of maladministration during the migration (one of many!)
The cl says that they have letters to show ongoing payments or CB ESA and IR ESA including the SDP and EDP.

All well and good but the cl claimed UC some time ago, was paid UC for one AP and UC then ceased over Notional Capital. Surely the IR ESA claim was abolished by the UC claim and should not be in payment?

Any thoughts?

If there had been an unbroken award of old-style ESA(c), that would be possible.  Income-related ESA is only abolished for the purpose of the UC claim and any award arising from it, so once that award ended ESA(ir) was unabolished as it were.  The problem though is that the UC claim also had the effect of converting the ESA(c) to new style, but whether that conversion is irrevocable I am not sure, this requires a delve into the WRA 2012 commencement orders - probably the no 9 Order.  If Charles is reading, he will have this at his fingertips and can save me the research!

In general the conversion to NS-ESA cannot be reversed. The only exception is if they were no longer able to claim UC at the point they became re-entitled to ESA(ir). For example, if they had more than 2 children and it was prior to the end of Jan 2019, or they lived in a live service area and it was after the live service was closed to new claimants (from the start of 2018).

Alternatively, perhaps this was a case where the claimant breached the SDP gateway.

Perhaps most likely of all is that DWP have simply made a mistake!