Hi there Micmat,
Happy Monday. This is related to settings on your server. The cause for this is related to limitations on your website’s hosting server, specifically in the PHP settings. Please work with your web host to increase your the max_input_vars setting. Additionally, for very large forms you may also need to increase your PHP process times so that saving the form does not timeout.
Hope this helps,
Joseph
VFBPro Support
P.s. Since you are a pro user, you may also feel free to use our paid support at vfbpro.com.