I do not have the problem in my tabhost that you are having with yours, Try this:
If this does not solve your problem, perhaps a more qualified forum user can offer the correct solution.
This is the how the default TabHost looks on Android 4+.
You can use this sub to disable this:
Sub PreventUpperCase(th As TabHost)
Dim p As Phone
If p.SdkVersion >= 14 Then
Dim jo As JavaObject = th
Dim pnl As Panel = jo.RunMethod("getTabWidget", Null)
For Each v As View In pnl.GetAllViewsRecursive
If v Is Label Then
Dim j As JavaObject = v