[Bug] AddItemAsync add item in wrong index.

[gaffkins]

Steps to reproduce.

• Init collection with 3 items : 1,2,3
• Some sort elements: GetDataAsync return 2,3,1
• After add new element GetDataAsync return 2,3,4,1 instead 2,3,1,4

After use AddItemAsync should I use ResycAsync? Because without it application throw exception.

[jbomhold3]

Try 2.0.0-Preview1