Given no other node sees the TX even hours after blockcypher accepts the TX I'm beginning to wonder what they are doing with the TX and whether or not they rebroadcast it, or just hold it in their mempool for ~ 18 hours?
We don't know the exact behavior of blockcypher, but assuming they do, they can't broadcast to another node which have different rule such as don't accept transaction with non-standard script (which is OP problem) or only accept transaction with fee at least 1 sat/vbyte.
So what I'm wondering I guess is is blockcypher mining and therefore (maybe) going to add the tX to a block if/when they find one? Or, are they just reporting that the TX has been "broadcast" (albeit just to their node) and no one else is picking up the TX to mine it?