Fatal error trying to create slider from sample

I’m getting a fatal error when I try to create a slider from one of the provided samples. It does create a slider, but there are no images.

I’m using WP 5.3.2 and current Master Slider.

Here’s the message (I replaced long path prefix with xx):

Importing Master Slider

Importing slides ..

Slider “2” created successfully.

Media “121.jpg” already exists.
Media “121.jpg” already exists.
Importing ( /2012/10/2.jpg ) file ..

Fatal error: Uncaught Error: Using $this when not in object context in xx/wp-includes/class-http.php:622 Stack trace: #0 xx/wp-content/plugins/master-slider/admin/includes/classes/class-msp-importer.php(662): WP_Http::get(‘http://demo.ave…’, ‘/home/customer/…’) #1 xx/wp-content/plugins/master-slider/admin/includes/classes/class-msp-importer.php(599): MSP_Importer->fetch_remote_file(‘http://demo.ave…’, ‘/2012/10’) #2 xx/wp-content/plugins/master-slider/admin/includes/classes/class-msp-importer.php(555): MSP_Importer->download_media(‘/2012/10/2.jpg’) #3 xx/wp-content/plugins/master-slider/admin/includes/classes/class-msp-importer.php(502): MSP_Importer->fetch_all_medias() #4 xx/wp-content/plugins/master-slider/admin/includes/clas in xx/wp-includes/class-http.php on line 622
There has been a critical error on your website. Please check your site admin email inbox for instructions.