Q: Remote Disc on Macbook 2015 doesn't work.

Hi, Morgan.  

Thank you for visiting Apple Support Communities.  

I understand you are no longer able to use the shared disc option on your Mac.  Let's start with resetting the SMC, NVRAM and then test using this feature.

Resetting the System Management Controller (SMC) on your Mac

How to Reset NVRAM on your Mac

If the issue persists, make sure both systems settings have been enabled for this feature.  

Use the CD or DVD drive from another computer with your Mac

If the issue persist, please let me know more information on the other system and the Mac OS X  or Windows version being used.  

Cheers 

Hi, Morgan.  

Thanks for the follow-up.  Were you able to go through any of the other troubleshooting steps that I recommended?  If so, can you let me know what happened after each step? 

Cheers

Morgan, 

Thanks again for the follow-up.  I think the best option to further assist you with this would be to reach out to us via phone.  

Contact Apple for support and service

Cheers