Suffering this problem with 2.7 which also affects the Explore tool, and whilst I can get that tool to display by resizing it, the scroll bars don't work and my screen isn't big enough to fit all the fields from some of my feature classes
Thanks @yunmeiHuang for your solution to the log in screen. I wasn't able follow your process very well unfortunately, but found that by moving the mouse cursor up from the mid left bottom, I could identify the OK button, then the password and username fields by the shape of the cursor, then paste them in.
Thanks also to @AgostinoCirasa_sitr . I can confirm that your registry solution works, at least for the Explore tool. I haven't needed to log in again since. Though I'm not sure this is something your users should be required to do ESRI
I have since had two updates and now on 2.7.2, neither of which were to address this issue. Using 2.4.2 at work and this is not a problem.
Edit:
I wasn't keen on disabling hardware acceleration as I wasn't sure what the wider implications would be, so I wrote a python script to toggle the hardware acceleration off, start ArcGIS Pro, then wait a few seconds for it to read the registry, then toggle it back on. As the registry is only read at startup, it only affects ArcGIS.
Thereafter, all dialogs seem to be working (so far)
Edit: Updated to 2.8. No change to this issue