ok so ive been battling this all evening, resolve Studio wont render my project to H.264 MP4... it fails at 98% with this:

Render Queue
Job 1 - Trailer_v3 H.264 | 3840x2160 | 23.976 fps Completed
Job 2 - Wedding_Final H.265 | 3840x2160 | 25 fps | stopped at 01:12:44:08 Failed
Job 3 - Wedding_Social_9x16 H.264 | 1080x1920 | 25 fps Waiting
i restarted teh PC and teh app. Are there any known causes i should check first?
im under real time pressure, so a quick reliable worakround would be amazing. A proper explanation for next time would be great too, any pointer in teh right direction would save my week. thx in advance!!