Characters Added to Campaign Showing 8hp

[WrittenZero]

I am currently experiencing an odd error. I have 2 players that when joining my campaign are showing their max HP as 8, although their max hit points should be 24 and 28.

The whole situation:
I am running a Pathfinder 2nd edition campaign. We started at first level and everything was fine. The players hit level two and someone asked about an option in a book I hadn't bought. I went and bought it but I couldn't enable a new book on a campaign already in progress. So I started a brand new campaign.

When adding characters to the new campaign it was noticed that 2 of the characters for some reason had max hit points listed as 8. Both characters happen to be gnomes, although every other aspect of their characters is different. One character was created and owned by me (For a player that doesn't use HLO and I just print it out for him) It is currently in GM Controlled PC's. The second character was created by the player and imported to the campaign. It is currently in Member Controlled PC's.

Both characters were fine as level 1 characters in the original campaign. This only arose when adding these level 2 characters to a fresh new campaign.