CC2530: After 8+hrs, CC2530 poll rate stops and is in plain sleep mode

Do you call NLME_SetPollRate in your application? How do you know device is not polling? Do you use Packet sniffer to check it?

NLME_SetPollRate is an API to change polling rate. I ask you use it or not to know if polling rate to be set to 0 accidentally. If you don't call NLME_SetPollRate in your application, it's not a problem. I suggest you to make sure your application is still running when you see device is not doing polling.

Do you try to check if your application on CC2530 is still running or not when you see this issue?

I believe it is because when I press a button connected the CC2530, then the poll rate starts back up again.

I cannot judge what happens according to your description. I also suggest you to use TI packet sniffer or Ubiqua Protocol Analyzer to check what happens over the air before this issue occurs.