Hi there,
Thank you so much for getting in touch with us.
We are pleased to inform that our latest version 2.6.1 has integration with HPOS. In addition, even our version 2.6.0 (Discount Rules for Woocommerce plugin) can be integrated with HPOS.
It is advisable to update our plugin to the recent version (2.6.1) and have a check. You can refer to this guide to get more information on version updates: https://docs.flycart.org/en/articles/2258499-version-updates
Hope this answers your question.
Thanks
Team Flycart