i have an interesting issue... I hope I can describe it correctly....
I have a HUGE library, dating back to 2011. I have folders in Lightroom for each year (2011, 2012, etc...) I had a "2015" folder in there, but somehow it got separated from showing in Lightroom, so I have 2011, 2012, 2013, 2014, 2016... I do have the 2015 folder on the same drive as the other years, but it is NOT showing in Lightroom at all. And if I try to re-import anything in the 2015 folder, I get the error that there is a duplicate folder in the library. As shown in the picture, I have year folders on my L:\ Drive... well in reality I also have a 2015 folder on the L:\ drive as well, but I can't get it to appear in Lightroom. I'm not sure if it is supposed to show up under the C:\ drive or not. I'd just like to get them to appear in Lightroom...
I hope I described this issue clear enough. If anyone has questions I'll do my best to answer.
Importing a second time is always the wrong answer.
Right-click on the "amica" folder and select "show parent folder" to see if that helps resolve where that folder might be.
If you know LR is looking at the wrong drive for a folder, you can right-click "relocate folder".
For the missing 2015, do a library search for any of those images.
select one, right-click on it, "show in library folder".
select it again, right click, "show folder in Explorer".