I also am having trouble with the item filter in the admin using ver2.2.
For example, we have 4 items in there with the word "BrightFace" in the title.
Filtering on "brightface" works, but neither "bright" nor "face" produce any results.
Also, three-character strings don't seem long enough to filter on. I've tried several short strings like "QoS" "HD" "PCS" which are used commonly in our article titles and none produce results when used as the filter.
Also, common words like "Does" "What" etc. seem to be excluded from active filtering.