Hi All,
I have a Chinese elm that has been doing well indoors. But recently about 80% of the new buds seem to shrivel and die before properly sprouting into new branches. I have recently re-potted and root pruned. Not sure what is the problem. Any help with a diagnosis would be greatly appreciated

You cut of the roots. Not the tree cannot sustain itself.
Next time trim the plant while still dormant from winter. For now, give it dappled shade and water sparingly