Thanks for posting. You had reached out to us directly, but I’ll go ahead and include my response in this public post:
Looking at the specifications via the link you provided (thank you!), the USB-C port does claim support for “Power Delivery”, which typically would mean that it can charge the host through the USB-C port. However, I investigated further into the user manual for this system (http://h10032.www1.hp.com/ctg/Manual/c06140602, retrieved from https://support.hp.com/us-en/product/hp-envy-15-cn1000-x360-convertible-pc/23238176/model/24771787/manuals), and unfortunately it appears that the USB-C port does NOT support Power Delivery for host charging:
You’ll notice that it does not explicitly state that the port accepts power to charge the computer (HP is good about including that in their use manuals). It is a bit misleading because while it states “with HP Sleep and Charge”, it actually is referring to the ability of the port to provide power to other devices while the system is off.
It looks like HP may have made a mistake on that product page by including the term Power Delivery. This is further evidenced by the fact that you were able to rule out the dock’s hardware since it charges another system. If I’ve misunderstood something, please let me know.
Sorry about the disappointing news here.