Yelp is moving 4-5 star reviews to not helpful.

Hi all,I’m currently helping a freind with his air duct cleaning business which over the years was not managed at all on social media.I was going through his yelp reviews and most of them are positive but are put in the “not helpful tab” while his 2 negative one star reviews are highlighted as helpful. The same thing is happening on some other accounts.TDLR Does his service suck or is it a glitch?Thanks via /r/business https://ift.tt/2FtgVDI