Hi there,
I use MAMP on my Mac running High Sierra 10.13.3 (17D47) and I am developing locally. I have lifetime access to all of your extensions, so I use MetaBox, MetaBox Builder and MetaBox Tabs. I have all the latest versions.
Also these are the only plugins I use on my local install
Since updating to WordPress 4.9.4 every time I try to create a new metabox I get the following error
Notice: Undefined index: fields in /Applications/MAMP/htdocs/forge/wp-content/plugins/meta-box-builder/inc/class-meta-box-processor.php on line 61
Warning: Cannot modify header information - headers already sent by (output started at /Applications/MAMP/htdocs/forge/wp-content/plugins/meta-box-builder/inc/class-meta-box-processor.php:61) in /Applications/MAMP/htdocs/forge/wp-includes/pluggable.php on line 1216
I have created new installs with WP 4.9.2, 4.9.3 and of course with the latest version 4.9.4 and every time I try to create a new metabox, it's always the same error.
Any ideas what could be causing this?