After a more thorough investigation with other Hempcoin users, it appears that this may be a matter of technical incompetence that has put users funds at risk.
From what I have seen it appears that P2PB2B made a technical error with regards to the staking feature and have been sending free Hempcoins to users. Some of these users withdrew their free coins or sold them for BTC and now due to complete incompetence on their end they do not have the balance to cover legitimate pending withdrawals.
Instead of eating these losses due to their own incompetent tech team, they have decided to rollback legitimate trades from parties not involved in this tech error and canceling their orders from 2.5 weeks ago.
Additionally, instead of admitting their mistake, they have pretended that a fraudulent transaction took place. Here is their response to my support ticket.
"One of your buy orders from 2019-06-14 20:27:17 THC_BTC amounting to 565 343 THC was reverted in order to help you to avoid any financial losses. We discovered that THC`s, which the seller sold you during this deal, were obtained in a result of fraud. The amount of BTC you spent for this deal was credited to your account."
A quick check of any Hempcoin holders deposit history on P2PB2B will clearly show free coins being deposited over the last few months (appears to be from May 20th to June 2nd) and will look something like this.