Right to Work Check Failed

[CloudyNow]

I am a postgraduate student on a Tier 4 visa. I recently applied to a graduate scheme at a Big Four accounting firm who regularly sponsors Tier 4 holding international students for Tier 2 visas as long as they are RLMT-exempt. Although I passed all of their recruitment processes, they are unable to extend me an offer as the Right to Work check on my application failed. I had showed them my current Biometric Residence Permit, passport and a letter from my university confirming my course end date (which is 18/09/2018) but the test still failed. This graduate programme commences in September.

They refuse to tell me why exactly the test failed; they told me that they will invite me to their office some time this week or next week. Obviously I want this sorted as soon as humanly possible, so I want to predict any issues that arise when I go to see them in the office.

I suspect that they might say that I cannot apply for a visa on time because my course barely ends in September and my results won't be confirmed on time for me to get an exemption from the dreaded RLMT. My comeback to this would be the fact that I also did a Bachelor's degree in the UK on a Tier 4 student visa, which means I am not reliant on my current degree results to get an exemption from the RLMT.

Is there anything else that they may have cause the right to work check to fail?