I have the following right now which works fine if the string is alphanumeric and separated by commas, but it doesn't work if I only have a single string.
Works for something like "1A,1B,1C", doesn't work on "1A"
Sorry, I don't know much about regex and I only got this through searching.
Here are a few example of what can be valid or invalid
1 - Valid
12 - Valid
1A - Valid
A1 - Invalid
12A - Valid
A12 - Invalid
1AA - Invalid
A - Invalid
1,2,3,6A,6B,11,11A - Valid
Invalid would be if any other characters appear in the string except for numbers and letters also no commas or anything in the prefix and suffix