Books (10.14): Text not visible when run on eGPU-controlled display

Number:rdar://44032251 Date Originated:2018-09-01
Status:Open Resolved:(10.14.3)
Product:macOS (Books) Product Version:10.14 beta (10A377a)
Classification:Serious Bug Reproducible:Always
I am running the 10.14 Mojave beta (10A377a) on a 13" MacBook Pro with an eGPU (the Developer edition). When I launch the Books app with its window on the display attached to the eGPU and open a book, the text of the book is not visible.  Turning off the eGPU and relaunching Books restores proper behavior and the book is visible again, as does dragging the Books window to the MacBook's internal display and restarting.

Steps to Reproduce:
1) Start up a MacBook Pro (13-inch, 2016, Two Thunderbolt 3 ports) with an External Graphics Development Kit connected (via an Apple Thunderbolt 3) cable. The eGPU is attached to a Dell P2715Q monitor running at 3840x2160 resolution with a USB-C to mini-DisplayPort cable.
2) Launch Books; if it does not appear on the external display, drag its window to the external display and then relaunch it.
3) Open a book.

Expected Results:
The text of the book is visible.

Actual Results:
The Books window is blank, except for the title of the book at the top of the window.


Workaround: Use internal display

I have discovered that if I drag the Books window from the external display controlled by the eGPU to the built-in display of the MacBook Pro, the text becomes visible. If I then drag the window back to the eGPU-controlled display, the text disappears again.

Problem not resolved in 10.14.3

After applying the 10.14.3 update, the problem initially appeared to be resolved — the text of books such as "The Swift Programming Language" was visible in the Books window, even when using the eGPU-controlled display. However, after a restart, the problem returns, and the text of ebooks is not consistently visible, even under 10.14.3. Sometimes part of the page is visible, but most frequently the text is not visible at all.

Problem remains through 10.14.2

This problem continues to exist in the release build of macOS 10.14 and in subsequent point releases. In my currently installed release of macOS 10.14.2 (18C54), the text of the book remains invisible, but the page index is visible in light grey at the bottom of the window. By scrolling horizontally with my Magic Mouse, I can make the page index advance, but the text of the book remains invisible.

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