When on the strategy page, if you have filled out builds and champion and ban lists, the entire page will reset if you try and update it with an invalid build.
Not sure if this entirely a bug, but it is kinda frustrating when the page gets entirely reset after spending some time on it.
1
We can look into that :) For now I'd recommend you save after each section, just to make sure you don't lose anything drastic if this happens.