Show Log not showing all revisions

I have an issue with Subversion not showing all revisions I'd expect to see when I look further down in the directory tree.

Let this be my directory structure:

trunc
  |____ src
         |____Folder1
                 |______File1

For File1 we have revisons 1, 2, and 3.

We're using Tortoise-SVN 1.8.11, current version at this moment, SVN 2.7.6.

In Windows 8.1's file explorer, when I do SVN Show Log off the trunk folder, it shows me all revisions. However, off src it only shows me revisions 1 and 3. (Same when I start in Folder1 or File1).

I did the same in Tortoise's repository browser, same result. Did a fresh checkout, same result.

I also use the AnkhSVN plugin for Visual Studio. This shows me all revisions (1,2,3) wherever I look!

This Tortoise issue is nasty because I prefer Tortoise over Ankh to merge branches. Of course I don't want to miss revisions while merging.

Does anyone know what's going on here and whether this can be fixed in any way?

After a lot of head-scratching while I was preparing this question, I concluded that this had to be a machine-specific issue, because on another machine all revisions were shown irrespective of the folder where I did "Show Log".

I found out here that Tortoise caches log messages. Now when I cleared these...

...I finally saw al revisions again.

I figured I'd still post this question, now with the answer, for others running into this deceptive issue.