Clients receiving CP-2100A (missing or "wrong" TIN number)

Hello, my clients are receiving CP-2100A letters from the IRS saying there is a missing or incorrect EIN / TIN on the forms they are submitting. The information in question is coming from the W9 form I provide to my clients. 

 

Some background: I own a single-member, "disregarded" LLC.  I have a personal EIN number (so I don't need to give out my SSN to clients) and I have an Business EIN number.

 

Per the IRS'  W9  instructions...

-I entered my name on line 1.
-I entered my business name on line 2.
-I entered my personal EINi n Part 1 because...

 

...the W9 instructions specifically say, "If you are a single member LLC that is disregarded as an entity separate from its owner, enter the owner's SSN (or EIN if the owner has one). Do not enter the disregarded entity's EIN.

I feel like I am following the IRS's W9 instructions to the letter, does anyone know why the IRS feels there is a mismatch with the EIN / TIN numbers...and what the fix is?   Thanks for your help!