Although Stake split threshold was set to 1.000 (1, not 1k), it divided initial UTXO on sub 1 tPIV UTXOs:
https://blockbook-testnet.pivx.link/tx/ea69251a41aaa6c0350523bb9410fa943cae2aff16112f692c09eef7b38aee53

NOTE: Possibly irrelevant info, but MultiSend feature was activated with 50+ different addresses.

Also, Custom Fee was set to 1 tPIV/kb.