Google analytics 4

Support for Google Analytics 4 was introduced in Showkase v1.7.5.

If you go to 'Site -> Site Settings' and expand the 'Google Analytics' section (at the foot of the page), you'll see a drop-down menu for the 'Tracking code'.
Version numbers are not mentioned but if you select 'Global Site Tag (gtag.js)' (and enter your 'Web property ID' above it), the code which is entered into your Showkase pages exactly matches the code shown on Google's own 'Google Analytics 4' support page here.

(Showkase still supports the older version of Google Analytics, too. Just select 'Legacy (ga.js)' from the drop-down menu for the 'Tracking code'.)

I hope this helps to answer your query.

Links sent!

You can find instructions for Upgrading Showkase here.

Notes:

(1) When upgrading your Showkase site, please be sure to make a complete backup of your existing site first, just in case anything should go wrong and you need to reinstate your original files at a later date. You should not encounter any problems upgrading Showkase but it would be wise to have a backup of your site should anything unexpected happen. Also, if you have made manual customizations to any Showkase source files, then please note that they may be overwritten when you upgrade and you'll need a backup in order to reinstate them afterwards.

(2) Please remember that Showkase-Standard comes bundled with Juicebox-Lite (the free version of Juicebox) so, after upgrading your Showkase site, you'll need to reinstate your Juicebox-Pro files by following the Installing Juicebox Pro instructions here.

It's probably just a browser caching issue.
Try refreshing the settings page (Ctrl + F5).
Otherwise, try completely clearing your browser's cache before reloading the settings page.
It should look like this screenshot: [Link removed.]

Showkase supports only the Web Property ID. If you need to add any extra parameters to the Google Analytics 4 code, then you'll need to add them manually to the Showkase source code.
Open your showkase/_themes/base/pagetypes/basetheme.tpl file in a plain text editor and you'll find the Google Analytics 4 code staring at line 10.
You can hard-code whatever extra parameters you like within this code and, after republishing your site (just click the 'Publish' button), the extra parameters will appear in the Google Analytics 4 code within all your pages.

Just enter the 'Web Property ID' in the Showkase interface (above the 'Tracking Code' input) and Showkase will handle the Google Analytics code for you (without the need to modify any source code manually).

I noted the basetheme.tpl file only because you mentioned other properties and if you want to add an additional Google Analytics property to the code (such as MEASUREMENT_ID_2 in the sample code provided here), then you would need to do this manually.

If you just want to use the 'Web Property ID', then Showkase can take care of this for you.