I hit the same roadblock unfortunately. My academic references were all in a different field and I hadn't really stayed in contact except with one professor, who sadly has died. I did see that there's an option to use professional references, so even though I haven't done this myself, one route you could consider taking is to get references from managers, colleagues etc. who can speak to your technical knowledge. I agree though with your general point that after being out of an academic environment for a while that requirement becomes challenging.