On Steam version of game. Use of Incubus Cum by a fully female PC results in Missing_Wang_Tag_Errors. Use of Incubus Cum modified by Musky Sap on a fully female PC results in missing wang errors and does not appear to generate the Messy Orgasm perk for said PC. I've only tried this with one dose of I.Cum(MS). Perhaps multiple doses would eventually result in Messy O.