Found one other person reporting the exact same issue in forum, with no fixes. When creating a new mission in mission editor, editing existing mission, etc., USSR vehicles are categorized as fortifications. When selecting 'tank' icon and placing a new vehicle, the option under "Category" is only 'FORTIFICATION", with Type options being "Armed house, bunker, watch tower, etc. Generated missions will place USSR vehicles, which operate as expected when flying the mission, but they are still listed as FORTIFICATION in the editor.
I ran DISM and SFC to ensure that my hard drive was clear of corruption (it was) and then ran the DCS repair tool. Repair tool reported running successfully with nothing downloaded. Same results.
I then deleted the \Eagle Dynamics\DCS World\MissionEditor directory and re-ran the repair tool. Curiously, it still said everything was fine. I launched DCS, which then crashed to desktop. I ran the repair tool again and it downloaded and created the MissionEditor directory.
I launched DCS and Mission Editor and the original problem still exists. I ran the repair tool yet again, it said it ran successfully, and the problem is still there.
This is a 'vanilla' (no mods other than purchased from store) non-Steam installation, updated to current version, but the problem goes back to earlier versions (since original installation several months ago). I thought I just didn't understand the editor, but now realize that there's actually a problem.
"2.5.2.20601",
"timestamp": "20180814-133132",
"arch": "x86_64",
"lang": "EN",
"modules": [
"WORLD",
"UH-1H",
"A-10C",
"P-51D",
"KA-50",
"P51D-HIGHSTAKES_campaign",
"A10C-REDFLAG_campaign",
"NEVADA_terrain",
"UH-1H_ARGO_campaign",
"PERSIANGULF_terrain",
"F-86F"