Show multiple term references as ID in one row I've got a view of nodes, displayed as fields. As each node may have references to multiple terms/tags, I would like to show all these tags. 

When I use field "term_node_tid", then I get the multiple values properly displayed in one row separated by commas. But instead of the readable term, I need the term-IDs. 

So I set up another field using "tid", but now only the ID of the first term is shown. There's no multiple value field setting, where I could tweak things. Any help much appreciated.
Change field Formatter

If you're showing the actual Content field you can change the Formatter. Instead of using Label use Entity ID under Formatter. 

This will output Term IDs instead of term names, and all the Multi-valued settings will apply the same way as for the names output. 

Rewrite results with TID replacement token

Another way or changing the field output in D8 views (if the Formatter option isn't available for example) is to use the Rewrite results &gt; Override the output of this field with custom text and enter the token for the TID in there. You can look up the correct token pattern under Replacement patterns below the Text area. 

That is also how you would get the TID to display instead of the name if you use the field Content: All taxonomy terms.