I get a warning "Research item limit reached – we've set a limit on the number of research items our members can add at once. Please come back later if you have more research items to add.".
You must wait 24 hours and the platform will allow you to include 3 other investigations. I understand that this procedure is not fair for researchers who registered late on ReserchGate and who intend to include all their past research, but it is a platform policy.
It is quite unreasonable to impose such a restriction. ResearchGate should reconsider this policy as it unnecessarily limits researchers' ability to share their work effectively.
Indeed, a very annoying policy, which adds to other dubious policies such as that of excluding relevant journals who use legitimate DOI providers and yet are not registered with the providers they approve of. And this includes European DOIs... I am not talking of small providers.