It happens to just about everyone as many have agreed in the past. For me it has only recently come on and that is because the building stage is complete. if I had more to build well I would be good but when I dont, I go into the model railroading hibernation. That is partly why I am planning a layout expansion so that I will feel enthuiastic to head down to the layout and do work. I am not big into operations. I just like to build and see the work I have completed ya know? I may run a train or two a few times thru the layout but then its over. So in order for me to get out of the hibernation mode I have to plan more layout work and it will begin soon.
Do as I do , start looking at individual scenes , and say to yourself , “what can I do to make this more realistic looking”. When I do that I find lots of work that is fun to do. Just little sections at a time.
I am the same way. To me scratchbuilding things, whether structures, rolling stock, scenery, detailed trackwork etc, and superdetailing them is the most enjoyable part of the hobby. I have a very small loop (for Large Scale) with a few sidings for some operation but I’d rather just watch the trains run through the things I built. All rolling stock I scratchbuild MUST operate flawlessly - no static models for me. After I finished building something, I too go into hibernation trying to think of something else to build. Luckily for us narrow gaugers, there are always more things to build since not too much is available commercially, however, I do like and use RTR locos. This fact is part of my attraction to narrow gauge and minority scales. I’d rather have a small layout that I can build things for and detail to the nth degree than a basement-sized one that is so-so with common items, however, I fantasize of having one of those Eastern type basements available so I can add on to the layout.
That happens to the best of us. I went thru that 2 years ago but jumped back after a couple months.