OTHER CLUES to the mystery:
1. Usually i store the LR catalog in a separate folder (than the original raw files).
I just opened the original raw file folder and saw xmp files next to each .nef file.
these are the LR sidecars, correct? why are they in this folder and not in the separate LR folder that i created? (see screen shot above)
2. why does the screen shot above have four LR items? (with two greyed out - unable to access). All my other shoots show only two LR 'items' in the folder (one 'data', one 'catalog')
3. per the screen shot above - the end of the extension (for the two greyed out items) shows 'LOCKED' at the end of the extension.
SUMMARY: perhaps the catalog i need is 'locked out' or hidden somewhere?