AD71056 voltage reading at No load / Load switching condition

Dear sirs,

AD71056 has some questionable operation.  

Test setup: a relay connects a load, then the system waits a few seconds (MCU counts the pulses from AD); then the relay disconnects the load, system waits awhile and cycle restarts. AD71056 operates in high frequency output mode (which is 2 KHz). The relay is between AD71056 and the load, that is, AD71056 itself is constantly powered.

In this setup AD71056 periodically reads a doubled value, for  example

[2491s] Test #415: 184 (OK)

[2497s] Test #416: 186 (OK)

[2503s] Test #417: 382 (OK) <<-- doubled impulse count!!!

[2509s] Test #418: 191 (OK)

[2515s] Test #419: 189 (OK)

Can it be that the part itself returns from no load incorrectly?