Hi @okarun,
There isn't a minimum hard coded in or anything, but there is a dust threshold level of delegated POB that generate less than .001 HIVE (theoretically .001 HIVE would be the smallest payout, so you are ok.)
Luckily you did receive a payout last week, and you should receive a larger one this next payout distribution. I think the issue might have been that you were looking for a payment from @pob.voter account when the payouts actually come from @pob.bank, here is a screenshot of the payment I found below:

The same goes for delegating BEE to @bee.voter, the payouts will come from @bee.drone. Both give a pretty hefty return which is very stable and expected to grow. BEE.VOTER has a higher return of the two since the token is more valuable it generates more revenue.