Steps to reproduce the issue

• Log into back-end
• Navigate around

Expected result

User stays logged in so long as they continue performing actions before session expires

Actual result

Occasionally, user is logged out even when session has yet to expire. No error/warning message is given (ie. Warning! Your session has expired. Please log in again.)

System information (as much as possible)

Setting | Value
PHP Built On | Linux site.ca 3.10.0-714.10.2.lve1.5.19.3.el7.x86_64 #1 SMP Tue Aug 7 21:33:29 EDT 2018 x86_64
Database Type | mysql
Database Version | 5.5.5-10.1.26-MariaDB
Database Collation | utf8_general_ci
Database Connection Collation | utf8mb4_general_ci
PHP Version | 5.6.31
Web Server | LiteSpeed
WebServer to PHP Interface | litespeed
Joomla! Version | Joomla! 3.9.0 Stable [ Amani ] 30-October-2018 14:00 GMT
Joomla! Platform Version | Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT
User Agent | Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3602.2 Safari/537.36

Setting | Value
offline | 0
offline_message | Ce site est en maintenance.<br /> Merci de revenir ultérieurement.
display_offline_message | 1
offline_image | 
sitename | Site name
editor | tinymce
captcha | recaptcha
list_limit | 20
access | 1
debug | 0
debug_lang | 0
dbtype | mysqli
host | xxxxxx
user | xxxxxx
password | xxxxxx
db | xxxxxx
dbprefix | xxxxxx
live_site | 
secret | xxxxxx
gzip | 1
error_reporting | default
helpurl | https://help.joomla.fr/index.php?option=com_help&keyref=Help{major}{minor}:{keyref}
ftp_host | 
ftp_port | 
ftp_user | xxxxxx
ftp_pass | xxxxxx
ftp_root | 
ftp_enable | 0
offset | America/New_York
mailonline | 1
mailer | mail
mailfrom | xxxxxx
fromname | xxxxxx
sendmail | /usr/sbin/sendmail
smtpauth | 0
smtpuser | xxxxxx
smtppass | xxxxxx
smtphost | localhost
smtpsecure | none
smtpport | 25
caching | 0
cache_handler | file
cachetime | 15
cache_platformprefix | 0
MetaDesc | 
MetaKeys | 
MetaTitle | 1
MetaAuthor | 1
MetaVersion | 0
robots | 
sef | 1
sef_rewrite | 1
sef_suffix | 0
unicodeslugs | 0
feed_limit | 10
feed_email | none
log_path | /home/site/domains/site.com/public_html/administrator/logs
tmp_path | /home/site/domains/site.com/public_html/tmp
lifetime | 70
session_handler | database
shared_session | 0
memcache_persist | 1
memcache_compress | 0
memcache_server_host | localhost
memcache_server_port | 11211
memcached_persist | 1
memcached_compress | 0
memcached_server_host | localhost
memcached_server_port | 11211
redis_persist | 1
redis_server_host | localhost
redis_server_port | 6379
redis_server_auth | 
redis_server_db | 0
proxy_enable | 0
proxy_host | 
proxy_port | 
proxy_user | 
proxy_pass | 
massmailoff | 0
replyto | 
replytoname | 
MetaRights | 
sitename_pagetitles | 1
force_ssl | 0
session_memcache_server_host | localhost
session_memcache_server_port | 11211
session_memcached_server_host | localhost
session_memcached_server_port | 11211
session_redis_persist | 1
session_redis_server_host | localhost
session_redis_server_port | 6379
session_redis_server_auth | 
session_redis_server_db | 0
frontediting | 0
cookie_domain | 
cookie_path | 
asset_id | 1
debug_lang_const | 1

Additional comments

This bug has been really bothersome. I can;t pinpoint an exact action that causes it, it just seems to be random. Although, I've noticed I get logged out far more frequently when trying to check for updates/perform updates. Not sure if it's coincidental or related.