When I received a separate error message in ArcGIS Online, it helped me to determine the root cause of my issue documented here: Solved: Re: Editing Error in Cemetery Data Management Solu... - Esri Community.
That lead me to several posts (below) discussing various issues with how true curves are handled in various Esri products and apparent changes in that behavior over time.
As of now, I'm able to recreate the issue consistently using ArcGIS Online and ArcGIS Pro 3.3.2. If I buffer a point feature class in ArcGIS Pro with a radius of 12" to 24" and publish that as a hosted feature service in ArcGIS Online, I'm unable to move the polygons with the edit tools. I receive errors "Edits could not be saved: A non-true curve client cannot overwrite a curve geometry with a non-curve geometry." in ArcGIS Online and "Move Failed. Geometry cannot have Z values." in ArcGIS Pro. I believe the ArcGIS Pro error is erroneous - Z values are not enabled and the error documentation says that "it occurs so rarely that the typical causes have not been identified so no solution is available at this time" (160163: The geometry cannot have z values.—ArcGIS Pro | Documentation).
If I run the Densify tool on the feature class before publishing to ArcGIS Online (creating additional vertices and connecting them with straight segments, rather than true curves, I'm able to move the features as expected. I believe there is an issue with how ArcGIS Online handles circular, true-curve polygons of that size.
Changing the settings to allow editing of true curves in ArcGIS Online did not resolve the issue for me (Manage hosted feature layer editing—ArcGIS Online Help | Documentation - Allow or prevent editing of true curve features (about half-way down)). In that document, it mentions: "By default, true curves can be edited, but only from clients that can support editing true curves without overwriting them with the line and vertex approximations (also referred to as densified lines). At this time, ArcGIS Pro is the only client that can edit true curves.". I'm not sure that's still true as of v 3.3.2.
This happens any time I create a buffer from points with a diameter of 12" to 24". I did not try this with a larger buffer size. Hopefully this helps someone that runs into a similar issue.
Related posts:
True Curves = True Evil - Esri Community
Modify vertices failed: true curves not allowed - Esri Community
True Curves in ArcGIS Online - Esri Community
