The below is not a definite reason for the change to limited it is only possibilities of what may have happened as the OTC doesn't go through and analyze each company. My thought is that they have filed so many NTs in a row that it signals an inability to file by the initial due date even thought the SEC definition of an NT does not render the filing late.
In regard to the below comment, I would be surprised if you found that greater than 1% of the value they hold in shares has been converted. They can't convert without filing a Form and looking back...I believe I am pretty close to being correct on my calculation.