HB ending temporarily due to childcare costs ending ... triggering UC

This is an odd one.  Claimant no longer had childcare costs so informed Tax credits - there was a 28 day run on.  But the childcare costs disregard in HB has ended from the date the childcare costs ended even though the amount of Tax Credit was the same.  Which meant that there was no HB entitlement for a period of weeks because income was too high (claimant only had around £20pw HB).
She would now qualify for HB again if only she was able to claim it ... but UC

So there is no mirroring of the Childcare costs run-on in HB?