C881W-A-K9 routers running 15.1 and 15.2 are also failing to poll correctly. However, I can confirm that C881SRSTW and C891W routers do poll correctly.
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I think its best to open a TEC case with cisco to understand, if there is issue with the hardware or the software.
Here are Release 15.2(4)M Caveats from cisco.com
Answer: Turned out to be a cisco bug with Cisco C881W-A-CVO-K9 routers and all current IOS(couldn't find a working IOS). I opened a case with Cisco TAC and they created a bug and published a working IOS image for me.
If you need the working image it is called "c800-universalk9-mz.SSA.V153_3_M1-CSCul56697" and you will need to open a TAC case to get it. Hopefully they will release a fixed mainline version soon.