Okay, here is what I got.
After hitting the “Map” button, the following shows up on console:
load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:9 JQMIGRATE: Migrate is installed, version 1.4.1
admin.php?page=connections_csv&action=map:439 GET http://localhost/?ai1ec_render_js=common_backend&is_backend=true&ver=2.5.16 net::ERR_CONTENT_DECODING_FAILED
And then after clicking “Import” the console shows:
load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:9 JQMIGRATE: Migrate is installed, version 1.4.1
admin.php?page=connections_csv&action=import:462 GET http://localhost/?ai1ec_render_js=common_backend&is_backend=true&ver=2.5.16 net::ERR_CONTENT_DECODING_FAILED
VM626:2 Uncaught SyntaxError: Unexpected token ? in JSON at position 1
at JSON.parse (<anonymous>)
at Function.n.parseJSON (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:4)
at Function.a.parseJSON (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:9)
at Object.<anonymous> (admin.php?page=connections_csv&action=import:413)
at i (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:2)
at Object.fireWith [as resolveWith] (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:2)
at y (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:4)
at XMLHttpRequest.c (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:4)
n.parseJSON @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:4
a.parseJSON @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:9
(anonymous) @ admin.php?page=connections_csv&action=import:413
i @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:2
fireWith @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:2
y @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:4
c @ load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils&ver=4.7.2:4
The “ai1ec” referenced there is the All In One Events Calendar plugin, I’ll try disabling that and see if that makes a difference.