Unknown column 'b.unsubscribe_date' in 'order clause'

Hallo,
there seems to be a problem when users unsuscribe from a List AND there is a unsucribe confirmation email used in the list.

1. Unsuscribe via link in Newsletter Email
If an unsuscribe Email is used and a user klicks on the unsuscribe link inside the newsletter email, the following error is displayed onthe web page:

Error 1054
Unknown column 'b.unsubscribe_date' in 'order clause'

2. Unsuscribe via Profile:
When a user unsuscribes from a list via his profile on the web page the followin error occurs:

Ajax Request Failure

Cross checks / Verification
Nevertheless, in all cases the user is unsuscibed from the list.@
But no confirmation email is sent.
When i deactivate the confirmation email it works without errors.
When i reactivate the confirmation email the error occours again.

Versions:

• AcyMailing Starter 6.1.5 (latest)
• Joomla! 3.9.8

Edit, 15.06.2019, 15:27:
Just for the information. The opt-in with welcome-Email and confirmation link works. Also the opt-in for a list via the user profile works.

BR
SRN

Remi_Acyba

Go in your configuration -> security and then at the bottom of the page, click on the button
Check database security

I perfomed this check and got a "green checkmark".
The error still exists:

Error 1054
Unknown column 'b.unsubscribe_date' in 'order clause'

May helpfull for you... It was a fresh installation - no update from a previus version - of 6.1.5 (downloaded on 15.06.2019).

I checked the database manually, i.e. looking inside with phpMyAdmin:

• The column "unsubscribe_date" is present in the table "#__acym_user_has_list".
• The entry in unsubscribe_date...
  • for subscribed users is NULL,
  • for a unsubscribed user is the correct date and time (example: 2019-06-17 19:27:36).

BR
SRN