Hi. I am making this post should anyone re-encounter this bug with a workaround .
Mac OS Catalina 10.15.7 on Macmini 2018 - 64GB Ram
Adobe Illustrator 26.0.1
1st Action. 'Looked' at my illustrator file on the cloud browser - prompted the file to open on the desktop. For reference, this file was originally illustrated on Adobe Illustrator for the Ipad ((Ver 2.0.1 & previous version) on Ipad Pro, 5th gen 12.9" 1TB (latest 2021) Ipad OS 14.8.1)) On the desktop, using the direct selection arrows, selecting an object filled with a gradient (Gradient Points on Ipad) located outside the canvas area, becomes a transparency and the primary color swatch in the tool bar turns white. No 'Undo' option is available (grayed out). Close file to preserve original settings without saving.
2nd. Relaunch Illustrator. Problem persists.
3rd. Check file on Ipad. Color fill is normal providing that Illustrator for the desktop doesn't autosave and sync - if not, a revert to previous version is required. Object is selectable on the iPad as expected.
3rd. Relaunch Computer. Problem persists.
4th. Using Illustrator for iPad, return the object(s) to within the canvas area. The object is now accesable in Illustrator for the desktop and behaves normally.
5th. Reproducing the bug on new files and simple objects does not reveal the bug. e.g. a gradient point fill in a square box(s) behaves normally. Several boxes and a few color gradients with two text boxes behaves normally. Complex art such as curves, several colors and fonts are probably needed to reproduce the bug.
Your expected result: Object should be selectable, movable and retail color settings. Actual result: Object looses its fill.
See video file
Extra notes: I've been indiscrminate in my setup while learn and be creative on the ipad. I've used an 'artboard' that is 64"x96" large and have created objects dozens of inches large. I've also have dragged my very large objects off the 'canvas' which I never did on the desktop. Reproducing these settings on a new file did not reproduce the bug. Suffice it to say, none of this needs to be that large, but being vector work, I really didn't care. In hindsight, I know scaling the artwork smaller won't look the same.
I found this bug report on this forum which seems to be a similar problem. It had six votes.