Just to be clear these are not issues with the Inventory System but an Art/Engine issue with 4.10
There seems to be issues with 4.10 and the FBX importer as well as this Physics assets in 4.10. I have never seen this flashing/Disappearing Item before when attaching to sockets and I have been using unreal since 4.4.
These issue were not present in 4.9.2 and I noticed a lot of issues with 4.10 over the last few days working with art on another project.
Let’s hope they are fixed with 4.11
And you gave it a physics asset?
If you want it to be an instant 20 health set the duration to 0. If you want it to restore 20 health over 5 seconds (4hp a sec) set the duration to 5.