Hi Dani,
Thanks for reporting here, and for providing some background on what you have and what you’ve tried.
Based on that information, and especially because ‘hidden widgets’ are involved, I feel like I will probably have to blame that ‘feature’ there. Hidden widget (using widget Visibility) are a very interesting way of changing the content/layout of your page, but I’ve seen some combinations that cause fairly inexplicable behavior. That’s why we don’t actively recommend them often. But you’re certainly not the only one using it.
Most of the behavior is caused by the way hidden widgets _are_ actually always part of the page, but hidden in a way that some Widgets don’t seem to appreciate all the time.
For charts you’d have to imagine that for determining the ‘resolution’ available for rendering, it will try and measure its width. Which of course depends on the area it is displayed in, but widgets tend to care only about their own elements (as they should) and so it will measure ‘itself’.
Being hidden though has the effect that the measurement will end up impossible, or 0 (zero), which is of course no good for the logic that follows after…hence the notification and the toggling of the problem situation when you try it on other widgets. It is all about their initial state.
Not many widgets do anything with measuring in this way, so you normally don’t encounter this for anything else. Apart from the side-effects we’ve seen for very heavy pages with many hidden widgets that all contain lots of data (read: dozens of table widgets hidden with complex multidimensional data, annotations and other features in use).
Without having examined the screenshot in too much detail: is this a regular Line Chart Widget and could you switch to a Combination Chart for this? I think it does not ‘measure’ in the same way, but might be wrong.
If it already is a Combination Chart: could you make the contents of the chart change by setting a different ‘Named View‘ for a single widget, instead of swapping in and out individual widgets?
If none of that applies to your situation, then I can currently only think of a (soon to be released) new feature called Tabbed Pages, which allows you to efficiently show entire pages (read: widget or widgets) in an area, like a tab, and control which ‘tab’ is being displayed from the model, even while hiding the available tabs. It will be a very good alternative to hidden widgets.
Hope some of that helps. Feel free to ask for more support or explanation if you need directions.