Events Calendar Multisite 404 for events

I haven't seen any solutions that work for me or apply to my use case.

but, I have a url like

https://www.example.com/site1/event/some-event-2017-01-17/2018-08-30/

this will throw a 404 page not found (the default 404 for my WP install)

but https://www.example.com/site1/event/other-event-4-2017-10-28-2018-03-03-2018-09-01/

will load the event. I don't really know what may be causing the 404, but:

1. is it because i don't have a Multisite license for Events Calendar Pro?
2. the htaccess rules don't cover that many segments in the URI?

this is the htaccess i am using:

# BEGIN WordPress Multi-Site
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?([_0-9a-zA-Z-]+/)?([_0-9a-zA-Z-]+/) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]
# END WordPress Multi-Site