Hi Felix,
Not sure what exactly happening at your end. Can you please check the maximum execution and upload the maximum size? I recommend you ask your web host to configure the following server settings with the specified values or more for the PHP.
memory_limit = 512M
upload_max_filesize = 512M
post_max_size = 512M
max_execution_time = 300
max_input_time = 300
max_allowed_packet = 16Mb
innodb_log_file_size = 128MB
allow_url_fopen = On
If that does not help, please provide login credentials for your site in a secure note to examine it further, including:
– WordPress Site URL & Login URL
– WordPress Admin username/password
To create a secure note, click the key icon underneath any of your posts.
Thanks