Invigorate grants increased healing effectiveness, which increases how much health is granted by your healing skills (such as Eterra’s Blessing on the Primalist). It doesn’t affect how much health regen you have.

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I tested Sigils of Hope and I received 25% increased health regen for each Sigil I had active, so this is working as intended as far as I can see.

I double-checked this and appears to be working as intended. If you see abnormal behaviour still by doing the same as Hacka above, just provide a screenshot or screenshots and we’ll take a deeper look!