With the update to Numbers 11.0 on iOS, the ability to write rows to the spreadsheets apparently broke. After much cursing and hand-wringing, I’ve found a workaround, albeit a wonky one.
Apparently the problem is Numbers is taking too long to “get it’s **** together” and the shortcuts are sending info too fast, so essentially, you have to manually slow down the process.
To do that,
(1) I moved the Get File to the start of the shortcut (it’ll run in the background as the rest of the shortcut runs).
(2) I added an Open File right after the Get File (that seems to help, but I’m not sure why but saw it in other support replies).
(3) Then I collect all the data
(4) Finally I inserted a wait. On my iPhone 11 Pro Max I had to wait 10 seconds.
There’s still a delay in actually seeing the data appear, but I finally got it working after messing with it for a week.
One instance of this question seems to be getting some traction (my question from last week went ignored), in case you want to follow it https://discussions.apple.com/thread/252597941