Somehow, I have lost some of the editing graphics when working on my route. ONLY on my route.

Missing are certain mouseover visuals like the yellow lines highlighting loft/ribbon objects such as track. Also missing are the mouseover shadows of picklist items and the degree markers in my compass. There are other oddities too numerous to list here. It's odd because other graphics ARE present; for example, the N, E, S, & W of the compass are visible and "Selected" track displays the expected yellow ribbon upon the asset. Most non-linear assets highlight normally during mouseover. Another coinciding problem is that certain keyboard functions are not working, including the "Esc" key to bring up the exit/pause dialogs. "#9" key doesn't function but I can get to the 2D map using the icon on the compass. I checked the "Display" settings; everything is enabled except the sound domes.
IMPORTANT: This problem occurs ONLY when editing my Alleghany route. If I edit Chicago Yard, for example, everything is working fine. I have performed all the basic troubleshooting like reinstalling TS from Steam, Clear Cache, checking all my pc functions, etc. to no avail. After 3 days of troubleshooting, I am stumped. Am waiting for a response from RSC on this one. Meanwhile, I am painting terrain and placing scenery; cannot edit track or other lofts. Has anyone here seen this before? Any ideas what I need to check/fix??
Thanks,
Baffled Tori