There are a couple of things you can try.
First, try changing the ReplayType. ReplayType is a UFT Web Add-in setting. It can be used to change how the events are replayed on the browser. There are two modes of ReplayType:
*Event (1) - Replay of events using the Browser methods (something similar to DOM).
*Mouse (2) - Replay of events using the mouse and keyboard simulation.
Setting.WebPackage(''ReplayType'') = 2 'Mouse
Setting.WebPackage(''ReplayType'') = 1 'Event(Default)
So if you wrap your .Set code in that, it may resolve the issue.
If that does not work, try using DeviceReplay. This is similar to SendKeys (which may also work in this situation, but I have had more success with DeviceReplay). You can find details about this in Micro Focus documents [KM184330] and [KM1194127].
To use the method, .Click the WebEdit object that you want to change the value of, then use the following code:
Set DeviceReplay = CreateObject(''Mercury.DeviceReplay'')
DeviceReplay.SendString(''Your New Value'')
Set DeviceReplay = Nothing
I hope this helps.