We had the same issue. “Event list plugin upgrade in progress… Please be patience(sic) until this process is finished.”
Disabling and re-enabling the plugin a few times eventually sorted it out.
upgrade.log.584 has
[2018-05-16 10:12:07] Updated option "el_last_upgr_version" to value "0.8.2"
upgrade.log (and all the others with earlier timestamps) has
[2018-05-16 10:22:58] Update of option "el_last_upgr_version" is not required: correct value "0.8.2" already set
Something is wrong with the check for completion as we also got repeated error_log lines starting:
[16-May-2018 10:12:07 UTC] EL_UPGRADE: Maximum script execution time: 120 seconds
[16-May-2018 10:12:07 UTC] EL_UPGRADE: Option "el_upgr_in_progress" added with value "1526465527"
[16-May-2018 10:12:07 UTC] EL_UPGRADE: Start upgrade check
[16-May-2018 10:12:07 UTC] EL_UPGRADE: Updated option "el_last_upgr_version" to value "0.8.2"
[16-May-2018 10:12:07 UTC] EL_UPGRADE: Deleted option "el_upgr_in_progress"
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Maximum script execution time: 120 seconds
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Option "el_upgr_in_progress" added with value "1526465528"
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Start upgrade check
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Update of option "el_last_upgr_version" is not required: correct value "0.8.2" already set
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Deleted option "el_upgr_in_progress"
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Maximum script execution time: 120 seconds
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Option "el_upgr_in_progress" added with value "1526465528"
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Start upgrade check
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Update of option "el_last_upgr_version" is not required: correct value "0.8.2" already set
[16-May-2018 10:12:08 UTC] EL_UPGRADE: Deleted option "el_upgr_in_progress"
[16-May-2018 10:12:09 UTC] EL_UPGRADE: Maximum script execution time: 120 seconds
[16-May-2018 10:12:09 UTC] EL_UPGRADE: Option "el_upgr_in_progress" added with value "1526465529"
[16-May-2018 10:12:09 UTC] EL_UPGRADE: Start upgrade check
[16-May-2018 10:12:09 UTC] EL_UPGRADE: Update of option "el_last_upgr_version" is not required: correct value "0.8.2" already set
[16-May-2018 10:12:09 UTC] EL_UPGRADE: Deleted option "el_upgr_in_progress"
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Maximum script execution time: 120 seconds
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Option "el_upgr_in_progress" added with value "1526465530"
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Start upgrade check
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Update of option "el_last_upgr_version" is not required: correct value "0.8.2" already set
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Deleted option "el_upgr_in_progress"
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Maximum script execution time: 120 seconds
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Option "el_upgr_in_progress" added with value "1526465530"
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Start upgrade check
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Update of option "el_last_upgr_version" is not required: correct value "0.8.2" already set
[16-May-2018 10:12:10 UTC] EL_UPGRADE: Deleted option "el_upgr_in_progress"
The repeated section continues a lot.