Thanks for posting, and I would be happy to help!
Thank you for letting me know the dock and applications are working as expected outside of Citrix, as that lets us know where to focus. Citrix environment issues can be tricky to troubleshoot as there are many factors at play throughout the entire infrastructure, several of which are out of our control. We will certainly do our best to help, but just to set honest expectations up front we may not be able to provide a solution if the issue lies outside of our ability to affect change on the system.
Based on your description the mouse pointer is able to travel over the application and the window elements, but is not able to register click events. Using the Tab key to move the ‘marching ants’ selection indicator through the GUI elements works, as does the key press. Assuming my understanding is correct, it may be that Citrix is confused as to where the mouse pointer is actually located and clicking.
As a quick test, can I ask you to temporarily ‘move’ the display connected to the dock via the Display Settings application to the opposite side of your Surface display and test again?
To put it another way, in Display Settings two displays will be shown in total, the internal Surface Display (#1) and the external display connected to the dock (#2). These displays are most likely arranged logically in that the mouse pointer and applications travel between the two, for example #1 on the left and #2 on the right. In this case, please move the #2 display so that it appears on the left and the #1 display is on the right. While arranged in this manner, please test the same scenario again to see if the results are different.
Please let us know if that helps when you have a moment, and we will go from there.