TL:DR, if you are having issues with SKS64 not launching SSE, check if you are running and OSD program such as RivaTuner, disable it, and try again. Very similar to a handful of people I have seen commenting here and on other places, I suffered from the case where a command prompt whould briefly appear, with no further effect. Having attempted several times to fix this by 1. moving SkyrimSE and steam installation locations (away from C:\ drive), 2. reinstalling SSE, 3. downgrading to previous versions of both SSE and SKSE64 to no avail, and no appearent errors showing in either the SKSE logs or the Papyrus Logs, I finally found a solution which fixed it for me. For those which run into similar issues where launching skyrim via the SKSE64_loader does not work, check if you are running RivaTuner or a similar OSD program. I rememberd the Uplay overlay also failing to work when RivaTuner was running, and after taking a guess (more like a hail marry) and attempting to launch SSE using SKSE64_loader after having disabled both these programs it finally worked. I cannot confirm if similar OSD-providing progams also clash with SKSE64, or even take a guess at why it does it (as oldrim together with the x86 version of SKSE never had this issue for me). However, this completely solved any problems I had with launching SSE using SKSE64_loader, and I hope it does so for more people experiencing the same issues. EDIT: removed misinformation regarding MSI Afterburner.
