Topic: Redux Theme options selectbox Problems

I have this:

TypeError: a(...).select2 is not a function
redux.field_objects.select.init/</<()
field_select.min.js:1
.each()
load-scripts.php:2
n.prototype.each()
load-scripts.php:2
redux.field_objects.select.init/<()
field_select.min.js:1
.each()
load-scripts.php:2
n.prototype.each()
load-scripts.php:2
redux.field_objects.select.init()
field_select.min.js:1
a.redux.initFields/<()
redux.min.js:1
.each()
load-scripts.php:2
n.prototype.each()
load-scripts.php:2
a.redux.initFields()
redux.min.js:1
a.redux.tabCheck/</<()
redux.min.js:1
n.speed/d.complete()
load-scripts.php:4
n.Callbacks/i()
load-scripts.php:2
n.Callbacks/j.fireWith()
load-scripts.php:2
qb/i()
load-scripts.php:4
n.fx.tick()
load-scripts.php:4
field_select.min.js:1:918

result of this problem is that the select boxes in the theme options dont work.
currently only these plugins installed:
Akismet
WordPress MU Domain Mapping
WP Encrypt
WP Multi-Network
CMB2
Redux Framework
Slider Revolution
WPBakery Visual Composer
XStore Core