With IDA 7.4 [dropping backwards-compatibility](https://www.hex-rays.com/products/ida/support/ida74_idapython_no_bc695.shtml) for IDA 6.x, so will Sark.
Bugfixes will still be added to the IDA-6.x branch, but it will no longer be under active development. (Yes, I know development has not been active at all for a few years now...)