I have been working on a theme with modular website sections (Hero, CTA section, team section etc) and I have been using MB group and other MB plugins to dynamically render sections on the front end.
In the image above you can see what the wp admin looks like for a page. I can create a new section with the add more button and then select from the dropdown which section I want, as seen below.
All of this works like a charm, each section comes with its own settings where I can change the sections heading, subtitle, images etc. I am able to manage all the content via the data from the metaboxes.
I recently ran into an issue where after I have loaded 11 or 12 sections in the admin, I am no longer able to render any additional sections. I would select a new section as previously and hit 'Publish', everything would save as normal but when I refresh the admin page the most recently (last) added section would disappear, like it was never saved. It is also not rendering in the front end. This happens at around section 11 or 12, there is no rhyme or reason. I have no errors or anything. All the content still works, for the sections that were saved.
What could be the cause here? is there an internal limit to how many metaboxes you can display? This just doesn't make any sense.
I don't think there's any side effect. This configuration only increases the number of inputs submitted.
To avoid this issue in the future, reducing the number of inputs is the best way. However, I guess it's not feasible in this case. But as long as you keep the max_input_vars high, you don't need to worry about that.