Data tables 'refresh' button not working

I have a local instance running Galaxy 19.09. Unfortunately, the refresh button of data tables page of the admin section stopped working after the update from v.18.06 to 19.09 (but the problem has been there before in an earlier version 18.x. So the problem is probably on our side. Script- and Addblockers are turned off.

This is the log file message:
192.168.32.33 - - [07/Feb/2020:14:55:31 +0200] “GET /data_manager/reload_tool_data_table?table_name=rnastar_index2_versioned HTTP/1.0” 302 575 “http://galaxy.de/admin/data_tables” “Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:72.0) Gecko/20100101 Firefox/72.0”
[pid: 64299|app: 0|req: 5631/11867] 194.94.138.205 () {52 vars in 1154 bytes} [Fri Feb 7 14:55:31 2020] GET /data_manager/reload_tool_data_table?table_name=rnastar_index2_versioned => generated 575 bytes in 14 msecs (HTTP/1.0 302) 4 headers in 312 bytes (1 switches on core 6)

This is the Message from the browser debugger menu:
Error: “Request failed with status code 401” - DataTables.vue:103
exports createError.js:16
exports settle.js:17
onreadystatechange xhr.js:59

and here’s the script, that throws the error.

Maybe anybody has an idea or suggestion what is going on here? I would like to avoid permant restarts in of our productive instance.

Regards
Anne