The chain has syncing problems since the hard fork.  Many bad nodes there (old versions)  preventing syncing (like orphan correct chain).  Obviously the explorer blockchain is bitcoin longest chain,  the syncing has some math issue due to bad nodes there.

Even on same versions,  many miners are mining their own chain, not forming into one chain only yet. We are trying and communicating in discord now.  SO the issue is really a full node chain syncing problem, rather than a mining issue. 

When you mine a dead chain, sure you mined reward will be orphaned later.