Ignition doesn’t require tag and tag folder names to follow typical naming restrictions found in programming languages (not starting with numbers, not having spaces or punctuation, etc), but there have been numerous bugs where some part of the code has that expectation. The reporting module’s core is licensed from a third party where this appears to be prevalent.
IA will fix (probably, eventually, but not for end-of-life versions like v8.0), but the problem is likely never-ending.
You should avoid this problem by enforcing a policy of only using tag and tag folder names that are valid Jython identifiers. (That will make them java and javascript compliant as well.)