Fedora 28 - Kernel 4.17.7 - Display immediately goes into powersave logging into gnome

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I have 3 displays, one in Landscape configuration, the other two in "Portrait Right" configuration on either side of it.

This combination has worked well until just recently, after rebooting following a kernel upgrade to 4.17.7. The Gnome login screen appeared as normal on all three displays, but immediately after a successful log in the two displays configured "Portrait Right" immediately turn themselves off (go into power saving mode).

Playing around with the settings I discovered that configuring all three monitors to "Landscape" works correctly.

This is new behavior with 4.17.7.

Any ideas how to resolve this?