This has probably been reported, but I cannot find where. The issue can catch out the unwary.
Steps to reproduce.
Create a character, and as per normal don't change Hit Point Type preference from Fixed to Manual until after you have selected your race and class
Change Hit Point Type to Manual, and use Manage HP to ensure your Maximum Hits Points is accurate (Hit Dice value + CON modifier)
Increase Level to 2, and observe your Max Hits Points has increased by your CON modifier (remember the level 2 value)
Use Manage HP to note the Maximum Hits Points and Total Fixed Value HP (which should be different) then click Cancel
Increase Level to 3, and observe your Max Hits Points has increased by your CON modifier (remember the level 3 value)
Decrease Level back to 2, and observe your Max Hit Points has not reverted to the level 2 value as expected, but now equals the Total Fixed Value HP that you noted before (step 4).
You can repeat this by increasing and decreasing levels, and adding values for Rolled HP if you want, but whenever you decrease level(s), the Rolled HP will be reset so that the Maximum Hits Points equals Total Fixed Value HP for that level. This is valid behavior for Fixed HP, but not for Manual HP, and you are forced to remember what your Rolled HP is (all your Hit Dice rolls) in order to fix it, which is difficult if you've played several levels, and you have not been keeping notes.
Edit: The builder shows a warning on the LEVEL DOWN confirmation popup. It currently says: "Your hit points will be reduced by the fixed amount and class feature choices you have made for the higher levels will be lost." The part about the HP is factually incorrect. It says your HP will be 1) reduced, and 2) by the fixed amount. In fact, your HP is 1) reset (increase, same, or decrease) 2) to the Total Fixed Value HP for that level.
This has probably been reported, but I cannot find where. The issue can catch out the unwary.
Steps to reproduce.
You can repeat this by increasing and decreasing levels, and adding values for Rolled HP if you want, but whenever you decrease level(s), the Rolled HP will be reset so that the Maximum Hits Points equals Total Fixed Value HP for that level. This is valid behavior for Fixed HP, but not for Manual HP, and you are forced to remember what your Rolled HP is (all your Hit Dice rolls) in order to fix it, which is difficult if you've played several levels, and you have not been keeping notes.
Edit: The builder shows a warning on the LEVEL DOWN confirmation popup. It currently says:
"Your hit points will be reduced by the fixed amount and class feature choices you have made for the higher levels will be lost."
The part about the HP is factually incorrect.
It says your HP will be 1) reduced, and 2) by the fixed amount.
In fact, your HP is 1) reset (increase, same, or decrease) 2) to the Total Fixed Value HP for that level.