{Shift down} presses and holds the Shift key down, {Shift up} releases it.

In WhatsApp, Shift+Enter moves to the next line. This is how to simulate this in FastKeys

Create a Start menu item and select Run on Startup option - this will run the macro each time FastKeys starts.

I tried and it works on our computers. How long is the text?
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Thanks for the video. I tried to replicate this with the same exact commands but it works for me every time. There must be something else, could you contact us on our email to explore it further?

However, now that I'm back on "page one" and without pressing my right mouse button (gesture key) , using Right gesture opens the new tab alright, but on that new page Fast Keys stops working about half of the time until I press my right mouse button again. Sorry I cannot reproduce this. What do yo...

It looks like this hack has undesirable effects. Maybe try adding the following lines after SendLevel 0

Sleep 100
Send, {RButton Up}

Do you perhaps use a special language or keyboard Windows settings?

Can you disable all individual text expander items (and all phrase files) to see if some of them is causing the trouble?

Could you try resetting the Preferences to defaults?

Strange. Could you try resizing the window to max or min size and than close it?