At some point, I think fairly recently, something got messed up in the background tests of the ENMTools R package and it is building the models for the permutation tests using incorrect presence points. I think I've found the issue and am working on a fix right now, but if you're using a recent version from CRAN or GitHub to do background tests I would not trust those results until a fix gets released. I will do my damnedest to get that done this afternoon, Japan time. Really sorry for any inconvenience this might have caused.
edit: This issue has now been fixed and the fixed version is live on CRAN. If you've got any studies underway using the background test (similarity test), please reinstall ENMTools and run them again.