Quite likely (though it could also be a Yealink problem because not all phone manufacturers have this problem) but I agree with what Bullfrog said and I think the same...
People expect (and rightfully so) something which is certified to perform admirably with the product it is certified to work with and currently something in the FreePBX/Asterisk/YeaLink solution makes this very far from the truth...
And the FreePBX distro is a FreePBX/Sangoma product isn`t it not? It is affected by this problem and I don't think that someone who would invest a lot of money in that solution thinking that is is certified to work would be very happy with being told that his certified product doesn't perform correctly, that it is a known problem and that it is assumed that the problem is in another product made by another company but which is bundled with the FreePBX distro....
(A product that is a vital part of that solution...)
It's not important to know whose fault it is, your clients don't care, they just want something that works and certification is supposed to give that assurance...
Merry Christmas and have a nice day!
Nick