This is a post better suited for posting to the FM Pro forum. Report an Issue is intended for reporting possible bugs in the software.
Go To Related Records is acting on the window you have open, not on the original window. Thus, it brings up the related record in the floating window and then closes it before you can even see that it has done so.
Try this approach instead: (I am assuming both windows are on layouts that refer to CLIENT)
Set Variable [$ClientID ; Client::ClientID] //use your field names in place of mine
Enter Find Mode
Set Field [Client::ClientID ; $CLientID]
Great , it works !!!
Thanks a lot for your help , and sorry for for posting wrongly ;-) I will change that next time, as more problems will show up :-)