I use my desktop system for my recording studio. I have High Performance set and never sleep and I haven't had any problems with it reverting to what yours is doing.
I have had some power settings change after a Windows update, such as the Fall Creator's Upgrade. I am in the "Windows 10 Insider" program and get advanced Win 10 versions (dual boot on a separate drive with my production system). Every time I get a new version I have to update my power plan.
You could Create your own power plan (using the High Performance as the base) and see if that helps.
Here are some screenshots of my Power plan and the additional panels that allow access to create your own power plan.
Dell forum member since 2002
Dell Inspiron 15 - 5577 Laptop
Home Built Desktop PC with ASUS ROG Z170, i7 6700K CPU
Windows 10 64 bit Pro and Windows 10 Insider Program Beta Versions. SSD drives. Cakewalk by BandLab and Studio One 4.1 Recordng Studio Software.
Dell S2719dgf Monitor
Member of Nashville based R.O.P.E.