In admin interface not showing list of processed files

That sounds like some sort of permissions issue or some cache.

On your production site, please disable any cache plugin and check this:

a) Are there any files being created the directory wp-content/plugins/fast-velocity-minify/cache/ (check for example, using ftp or some file explorer).

b) When you go to the homepage and refresh (without any cache plugin) and then you view the source, do you see javascript and css files pointing to https://yourdomain.com/wp-content/plugins/fast-velocity-minify/cache/header-someletters-somenumbers.min.css or similar? And if yes, can you open it on the browser and see that it’s not empty?

c) When you go to the plugin settings and deselect all checkboxes and save, does it happen the same?

d) The SSL certificate should not matter (but are you behind cloudflare?), this opens the files directly from the hard drive for processing (does php have permissions for opening those css and js files?).

e) If you temporarily chmod 777 the wp-content directory recursively, does it work?

Thanks a lot for your reply

a) I find several files being created in the directory wp-content/plugins/fast-velocity-minify/cache/

b) I can open for example https://yourdomain.com/wp-content/plugins/fast-velocity-minify/cache/header-someletters-somenumbers.min.css or similar in the browser and the file is not empty

c) After saving again the same

e) Temporarily chmod 777 the wp-content directory recursively does not work

My productive site is https://www.dashoerwerk.de

There are no other cache plugins installed.

The List of installed plugins:
Aktive Plugins:
——————————
BackWPup
Companion Sitemap Generator
Disable All WordPress Updates
Fast Velocity Minify
Html5 Video Player
Maintenance Mode
Nextend Smart Slider 3 Pro
Precise Columns
Product CSV Import Export (BASIC)
Relative URL for Img and A Tags
WooCommerce
WooCommerce Germanized
Wp Mail Bank

Disabled Plugins:
——————————
CDN Enabler
Regenerate Thumbnails
WP Migrate DB

And here some server infos:

PHP-Version 7.0.8 (32bit)
MySQL-Version 5.5.50-log
cURL-Version 7.48.0
cURL-SSL-Version OpenSSL/1.0.2h

Verbindung zum Server selbst: Response-Test OK

Server Apache/2.2.31 (Unix)
Betriebssystem SunOS
PHP-SAPI cgi-fcgi
Aktueller PHP-User
Maximale Skript-Laufzeit 120 Sekunden
Alternative WP Cron Aus
WP Cron abgeschaltet Aus
Verzeichnis-Rechte 0755

Zeichensatz des MySQL-Clients utf8mb4
Zeichensatz der Website UTF-8
PHP-Memory-Limit 256M
WordPress-Memory-Limit 256M
Maximales WordPress-Memory-Limit 256M
Benutzter Speicher 14,00 MB

Geladene PHP-Erweiterungen: Core, PDO, Phar, Reflection, SPL, SimpleXML, Zend OPcache, bcmath, bz2, calendar, cgi-fcgi, ctype, curl, date, dba, dbase, dom, ereg, exif, fileinfo, filter, ftp, gd, gettext, hash, iconv, id3, idn, imap, json, libxml, lzf, mailparse, mbstring, mcrypt, ming, mysql, mysqli, openssl, pcntl, pcre, pdo_mysql, pdo_sqlite, posix, session, soap, sockets, sqlite3, standard, sysvsem, sysvshm, tidy, tokenizer, wddx, xml, xmlreader, xmlwriter, xsl, yats, zip, zlib

a) yes, you got it correctly
b) nice hint !
c) looking for source, yes …/fast-velocity-minify/admin.js is encluded
d) and it’s https://
e) I get a line JQMIGRATE: Migrate is installed, version 1.4.1load-scripts.php:9:542
f) firefox or chromium browser or another device the same

thanks for proposal – I will send you an admin login

There is a PHP function used there that goes into that directory and makes a list of the cache files, but according to https://php.net/manual/en/function.glob.php

Note: This function isn’t available on some systems (e.g. old Sun OS).
Note: The GLOB_BRACE flag is not available on some non GNU systems, like Solaris.

So for now, the plugin is not compatible with Sun OS or Solaris.
I will look into adding an alternative method on the next version.

Version 1.1.7 should have fixed the compatibility issues with SunOS and Solaris, please try again.

Yes, it works now. Perfect !