Tried new version 3.1.8. Attempt to rebuild the cache leads to this:
SELECT `tag_aai_lookup`, `tag_meta_app`, `tag_meta_area`, `tag_meta_id`, `tag_id` FROM `core_tags` GROUP BY `tag_meta_id` ORDER BY `tag_id` ASC LIMIT 0,100
IPS\Db\Exception: Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'support.core_tags.tag_aai_lookup' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by (1055)
#0 /home/support/public/system/Db/Select.php(346): IPS\_Db->preparedQuery('/*IPS\\advancedt...', Array)
#1 /home/support/public/system/Db/Select.php(408): IPS\Db\_Select->runQuery()
#2 /home/support/public/applications/advancedtagsprefixes/modules/admin/manage/tools.php(277): IPS\Db\_Select->rewind()
#3 [internal function]: IPS\advancedtagsprefixes\modules\admin\manage\_tools->rebuild()
#4 /home/support/public/system/Dispatcher/Controller.php(85): call_user_func(Array)
#5 /home/support/public/applications/advancedtagsprefixes/modules/admin/manage/tools.php(26): IPS\Dispatcher\_Controller->execute()
#6 /home/support/public/system/Dispatcher/Dispatcher.php(129): IPS\advancedtagsprefixes\modules\admin\manage\_tools->execute()
#7 /home/support/public/3uskbvr1xqi24czhwy51/index.php(13): IPS\_Dispatcher->run()
#8 {main}