Are you adding the infusions both as one you know and one you have active? The Artificer can know more Infusions than they can have Infused Items at a time. That's why the Infusions tab has 3 tables: Infusions Known, Infused Items on Hero, and Infused Items on Ally.
To use your examples:
- Enhanced Defense - Add it to Infusions Known, then add it to Infused Items on Hero. The second one will have a drop-down box for you to pick which of your armors you want it applied to.
- Bag of Holding - Add Replicate Magic Item (Table A) to your Infusions known, then add Replicate Magic Item - Bag of Holding to your Infused Items on Hero. You should then see a Bag of Holding in your inventory.
- Spellwrought Tattoo - Since this isn't in the regular lists of replicable magic items for the Artificer, it's covered by the Replicate Magic Item (Common) Infusion. Add it to Known, select the Spellwrought Tattoo from its list of common magical items, then add Replicate Magic Item (Common) to your Infused Items on Hero, selecting the same Tattoo from its drop-down. The only limitation here is that with the common magic item infusion, you need to then manually add the item to your Hero. We just can't program that one in a way that auto-adds any and all common items.