Is it possible there are decimals?
Have you tried add ROUND(…,0)?
Maybe this is related to the issue when things are lookedup or rolledup, the result is an array, not a number.
If that is the case the ROUND() function above may also show error.
Have you tried to do CONCATENATE() on both columns before you are comparing?
I would try that and then compare them as string. Since you are not doing any additional logic with numbers, then comparing them as string would do the job.
Here @Kuovonne has summarized well the issue with arrays… It’s not a problem in Airtable, rather Airtable doesn’t tell much and there isn’t much obvious guidance how to resolve it. So that may be the case here too?
If nothing helps, maybe provide link to sample data tables and share the table here.