Harvesting - what's wrong?

Hi,

I am using delegated harvesting under vistar’s node (angel.vistiel-arch.jp) from May 10th. The pretty weird situation happened at the end of May when I harvested 3 blocks in a very short period of time:

block number - date - time
205959 - 2021-05-27 - 13:02:51
216801 - 2021-05-31 07:27:34
231392 - 2021-06-05 - 09:08:20

So I mined 3 blocks in 8 days with only 26k coins. In 2021-06-25 I bought more coins and increased their number from 26k to 37k. From 2021-06-05 (112 days!) I didn’t harvest anything. Is it just bad luck after a lucky moment or something is going wrong? My harvesting status is active. I contacted vistar and his node is active all the time. I am collecting small rewards from his node which means I am connected correctly.

Accordingly, to the harvesting calculator, I should harvest one block per ~23days.

Link to my explorer: http://explorer.symbolblockchain.io/accounts/NDI66AADIUFE2MWIUACKSR2HPKB72CNLXMHM2RY

How the XYM harvester can be sure that everything is working well if he has to wait that long for rewards?

Best regards,
Bohucci