Upper case char in icon string causes exception

[Genfood]

Xamarin.Forms v3.6.264807

Tried on Mac and Windows

Support Libraries Version (eg: 23.3.0):

Xamarin.Android.Support.Design Version 28.0.0.1
Xamarin.Android.Support.v7.AppCompat Version 28.0.0.1
Xamarin.Android.Support.v4 Version 28.0.0.1
Xamarin.Android.Support.v7.CardView Version 28.0.0.1
Xamarin.Android.Support.v7.MediaRouter Version 28.0.0.1

Describe your Issue:

I figured out when I adding a ActionSheetOption whith an icon that I get an resource not found Exception. But only if the string contains an upper case char.
Otherwise it works. The icon-file name itself seems not relevant.

f.e.:

cfg.Add("Aus Favoriten entfernen",
                () =>
                {
                        ...
                },"StarDark");

Steps to Reproduce (with link to sample solution if possible):

Include any relevant Exception Stack traces, build logs, adb logs: