It has happened a few times now (enough for me to notice what may be causing this) that I open a webmap after overwriting a Feature Service that contains many layers shown in such webmap, to see that a number of layers just look wrong. I'll explain: I overwrite a Feature Service with 10 layers (points, lines and polygons) from ArcMap. Let's say that the Feature Service previously had only 9 layers, and I want to add an extra one, hence the reason to overwrite it. To do so, I ensure that no one is working on that webmap at the time, and I disable sync for this service in order to perform its overwrite. Mind, these is a non-editable Feature Service, as all 10 layers are only shown for background information on the webmap. So far so good, ArcMap gives me the success message and I move on.
When I see the webmap and turn different layers on and off, something looks odd. The contents of one layer have dissapeared, being the one that was placed at the bottom of the 'table of contents' in the webmap. However the layer stills seems to be there, but when turned on it shows the data of the layer above in the table of contents. To make it a bit more clear: layers 1 to 5 are ok. Layer 6 shows again the contents of Layer 5. Then Layer 7 shows Layer 6, Layer 8 shows Layer 7, and so on. Until Layer 10 shows the contents of Layer 9, and the contents of Layer 10 have been dropped from the webmap, into the uknown. This seems like extremely bizarre behavior, and I wonder if anyone else has experience something similar, and if there is something in particular I should be doing (or not doing).
On an additional note, when I originally created the webmap and loaded the original Feature Service (then with 9 layers), I did some re-arranging of the layer order and their names (as shown in the legend), different from what they looked like when published from ArcMap.
Thanks in advance for any light shed on this.