LibreOffice unable to select "English (USA)" - spellcheck not working

i was unable to use the spell checker in libreoffice 5.1.6.2 (and the problem appears intermittently with many versions). i'm using ubuntu 16.04, but the issue appears to be common on fedora and other ubuntu versions as well

not sure how common this bug is, but it's tough to track down so documenting it here

symptom:

• spell check fails to find any problems
• "Text Language" shows as "None"
• sometimes other options can be selected, but they don't work and it falls back to "None"
• clicking Style -> Edit Style -> Font -> Language, "English (USA)" is shown as an option, but it doesn't have an "ABC check" icon to the left

the fix:

• make sure hunspell-en-us is installed (that's the ubuntu package name)
• Settings -> Options -> Language Settings -> Writing Aids
• "Hunspell SpellChecker" shows up as ticked
• click Edit
• "Hunspell SpellChecker" shows as not ticked
• tick it
• spelling works

in short, the UI appears to get confused and believes a tool is activated, but clicking edit forces it to reload the true state and you can actually activate it

good luck