How to make spellcheck work on a doc created from a PDF in the writer?

Version 5, English Win 8.1, Writer. Created a .doc from a PDF from my HP 8600. When I run spellcheck auto or manual and I know I have misspelled words, spellcheck says all is OK. Spellcheck works on the .doc’s created thru Libre Office. Comparing the language, etc settings of the these two differently created documents they appear to be the same.