Almost every time I import new Persian texts into LingQ, it does not recognize many of my known words as known.
I have figured out that this is because different Persian fonts often use different unicode characters to represent the same letter. So if یک is written with ی and ک in one text you import, and with ي and ك in another, LingQ does not recognize that both are the same word, یک and marks it as unknown.
The solution is for LingQ to fix this and to recognize different unicode characters that are used more-or-less interchangeably in Persian as the same letter. I hope they can do this! I am not a programmer, but I imagine it would be easy.
Before that happens, though, the way to fix this for us LingQ users is to take the text we are importing and find-and-replace all the characters that LingQ is not recognizing.
I have found that the most common sources of confusion for LingQ are the following characters:
ی and ي
ك and ک
ة and ه
And of course we need LingQ to recognize the zero-width non-joiner (unicode U+200C)