f.lux + Shades = Flashing
I'm using f.lux 37.2 with a 2010 mini, 10.7.5, Apple LED display, ambient light engaged- no issues.
f.lux 36.5, 37.2, with a 2012 mini, 10.10.5, Dell u2711 display, Shades- flashing like crazy.
Shades* is a screen dimming prefpane I use because the Dell's OSD doesn't get it in anywhere dim enough for low-light use. It's positively blinding, and only gets brighter.
Shades worked very well until I installed f.lux. Now I get flashing from bright (as though neither app were installed) to dim (as though both f.lux and Shades were working).
As Shades is third-party software and a prefpane, I'm not hopeful the devs here can do anything for me. While I'd like to think there may be a fix coming, I mention this situation in case it may bring to light any help for the general population.
I haven't tried f.lux with an El Cap volume yet, but will advise my results.
Thanks for a fine app.
*Shades: http://www.charcoaldesign.co.uk/shades This is not the same as the app in the Mac App Store. This is freeware. I mention the URL only so the f.lux devs can take a look if they want.
f.lux and Shades don't work together, I'm sorry to report. Wish I had better news.