Bug report: Substitute producing invalid results with punctuation

**Describe the bug**
When using substitution, cyberchef is unable to produce the following decrypted ciphertext.

`.-_` should become, `_.-` but instead becomes `_-_` and warns that the ciphertext and plaintext are different.

**To Reproduce**
Steps to reproduce the behaviour or a link to the recipe / input used to cause the bug:

https://gchq.github.io/CyberChef/#recipe=Substitute('.-_','_.-',true)&input=Li1f

**Expected behaviour**

I expect the output `_.-`

**Screenshots**