Mass file renaming is broken.

[inkoalawetrust]

SLADE Version: 3.2.1
Operating System: Windows 10

Issue Details:
Ever since 3.2.0, it seems that the ability to mass rename files, such as for changing the names of sprite sheets -- has been broken, for example trying to rename all these sprites to use the name TNKT, while keeping the frame name and rotation steps, causes the file names to turn to this.

Meanwhile, trying to rename all the sprites to TNKT^&, so that they use the new sprite name, and also redo the rotation steps and frames. Also produced broken names, that look like this.

The file with the sprites I'm having this bug with are included below.

Chassis.zip