The rewrite is in <.htaccess>. Other rewrites work as expected.
Okay then I feel quite confident in concluding the query string is not in the form you expect. So I'll reinforce my earlier point that it is never a good idea to perform a match on more than a single parameter at a time in a query string using mod_rewrite. In the future, perhaps as part of this migration, you or a coworker might make a change that alters the appearance of that query string. Even an innocuous change that you don't believe will alter the query string might have the unexpected side-effect of doing so. And then your literal query string match will fail.
That was one of the many variants I have tried. It does not work
either. Since I cannot get logging to work either (grr), I cannot see
what is happening.
Rather than trying to set LogLevel to include more verbose logging of the rewrite module actions I would change the LogFormat to include the query string. For example, this is the one I use:
