The last update of the LTspice XVII Windows x64 executable was v17.0.36.0.
It looks like they've dropped the Roman version numbers, and also LTspice 17.1.x is now out of
beta.
The key change that's screwing with your carefully collected libraries is:
* Improved Installation. LTspice library files are stored in users’ %LOCALAPPDATA% directories, instead of My Documents
The fix for it is somewhat of a PITA - Ideally you should separate out the 3rd party or user generated models and symbols so you've got a clean user library
(n.b. You'll have to diff the cmp folder model files line by line, and strip the standard models) and add a user library folder to the control panel lib & sym search path tab (as <folder>\sym in the symbol path textbox and <folder>\cmp and <folder>\sub in the library path textbox.
A kludge that may work is to skip creating a clean user library and simply add the LTspice XVII library subfolders as above. However this has a high risk of accidentally using outdated models and increases the risk you wont include any 3rd party models and symbols when sharing your sims with others.
The user library is then accessible from the drop-down at the top of the 'Select Component Symbol' dialog.
You can do the same in LTspice XVII so you only have to maintain one user library going forwards. Rename your old lib and examples folders and reinstall and update LTspice XVII to get a clean standard library for it, free from user files.
N.B. if you collaborate with others, you should probably set up a shortcut to use a 'clean' copy of the standard library, without any user libraries and symbols that aren't in the sim's own folder. Do so by opening the file location of LTspice in your start menu, copying the shortcut and renaming the copy to
LTspice (clean) and adding the switch:
-ini "%APPDATA%\LTspice_clean.ini"
to the shortcut's command line. That will create a new instance with all control panel customisations reset to defaults the first time you open it
(but as usual 'sticky' once you change any starred setting), without affecting your regular LTspice's control panel settings. Use the new instance to open and run sims you intend to share, to see what will happen for anyone running a 'vanilla' LTspice, to check you haven't forgotten to include any custom models and symbols in the same folder as the sim. Its not foolproof as I have encountered sims and symbols with 'sticky' absolute paths in them which may not be easily visible, and can still point at your custom library folder(s). Personally I fix up such .asc and .sym files in a text editor, removing the absolute portion of the path, but you've got to know exactly what you are doing to get that right, so don't do it to your original files!
Hint: Set its background image to something other than the 'Antikythera Mechanism' default (or your usual one if different), so you don't get them mixed up when open.