Did a bit more testing on the same character. Toggled off the Sacred Defense stance before logout. Still lost HP upon log in, not as much though.
1532 HP 22 Temp
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1412 HP 22 Temp
120 HP difference this time.
Tried it with all gear removed
1284 HP
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1284 HP
Didn't lose HP this time. Checking what gear bonuses might lead to this.
Equipped 5 piece Epic Salt set. Things from the pieces I put on that affect HP is 32 Profane Lifeforce from Epic Anchorchain, Ins Con 4 from Epic Belt of Myriad Pockets, Con 9 from a aug in the belt, and Artifact Con 2 from set bonus.
1484 HP
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1364 HP
120 HP difference again. Perhaps gear calcs are the issue?
Another test: Equipped only Epic Shield of the Scorpion, 32 Profane Lifeforce and +2 Profane all stats.
1340 HP
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1340 HP
No HP loss.
Another test: Equipped only Epic Belt of Myriad Pockets with Con 9 aug. 13 Con total from the belt.
1428 HP
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1332 HP
96 HP loss. I have 30 con without the belt, 43 with it on. Con 9 would give +4 con bonus which would be 96 HP for my level 24 character.
When I had the full set bonus from saltmarsh I lost 120 HP. My guess is thus, set bonus and health coming from augment slots (perhaps only augmented con) is being calc'd incorrectly.
One last test: Equipped only Epic Shield of the Scorpion and turned my Sacred Defense stance on.
1765 HP
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1430 HP
335 Missing HP. 353 is my percentage bonus. I get 72 HP from the con from sacred defense, 25% of 72 is 18. 353-18 = 335. 335 is the percentage HP before the added con from the stance. % HP from a toggled stance also seems to be an issue.
Based on my above tests I don't think it's the feat bonus.