[Plugin: Gallery Bank Lite] No thumbnails generated

Hi!
I’m new to WP and I’m trying to set up my first site. The site is working, but when I try to generate a gallery with Gallery Bank the pictures are uploaded and I can view them when previewing the gallery, but there are no thumbnails generated. I tried setting permissions on upload folder to 775. No success. I’ve spent several hours trying to solve it. Without any luck so far. Debug mode is enabled and I don’t get any errors.
Any suggestions?

System status output:

WP Version : 4.2.2
WP Multisite Enabled : No
WP Remote Post : Success
Web Server Info : Apache
PHP Version : 5.5.24
MySQL Version : 5.1.73
WP Debug Mode : Yes
WP Language : Standard
WP Max Upload Size : 32 MB
PHP Max Script Execute Time :30s
PHP Max Input Vars : 1000
SUHOSIN Installed” : No
Default Timezone : Default timezone is UTC
Operating System : Linux?(32?Bit)
Memory usage : 18.5 MByte
SQL Mode : Not set
PHP Safe Mode : 5.5.24
PHP Allow URL fopen : Off
PHP Memory Limit : 256M
PHP Max Post Size : 32M
PCRE Backtracking Limit :1000000
PHP Exif support : Yes ( V1.4 )
PHP IPTC support : Yes
PHP XML support : Yes

### Plugins ###

Installed Plugins : Font Awesome Icons by Rachel Baker version 3.2.1Gallery Bank Lite Edition by Tech Banker version 3.0.115Max Mega Menu by Tom Hemsley version 1.7.3.1Page Restrict by Matt Martz & Andy Stratton version 2.2.1TinyMCE Advanced by Andrew Ozz version 4.1.9WP-Members by Chad Butler version 2.9.9.1WP-United: phpBB WordPress Integration by John Wells version 0.9.2.8WPtouch Mobile Plugin by BraveNewCode Inc. version 3.7.7

### Themes ###

Theme Name : Material
Theme Version : 1.1.3
Author URL : https://standew.com/klyment

### Graphic Library Settings ###

GD Version : bundled (2.1.0 compatible)
FreeType Support : Yes
FreeType Linkage : with freetype
T1Lib Support : No
GIF Read Support : Yes
GIF Create Support : Yes
JPEG Support : Yes
PNG Support : Yes
WBMP Support : Yes
XPM Support : No
XBM Support : Yes
JIS-mapped Japanese Font Support :No