The values (Price in Entry Currency and Fixed Price in Entry Currency) could be populated manually or from file with dots.
Then the red alert appears:
The user will then fix the dots with commas and click out from the field or press Enter.
At this point the red validation alert is gone as it is expected.
The problem is when you hit Submit – then you are stuck because of validation error which is not right as the value is already fixed.
Somehow the form recognizes that the value does not contain dots and the red validation error disappears but on Submit validation error is detected wrongly.
If the action rule on the Price in Entry currency field (see below) is removed then the issue is resolved.
a)- Price in Entry currency
However, that's the only way they have found to apply the comparison between both fields (Price in Entry Currency and Fixed Price in Entry Currency), whenever any of the those fields is changed, one needs to be greater that the other one.
b)- Fixed price in Entry currency
The issue is with rule "Execute rules for field Number_FixedPriceCurrency"
Sharing a fix for this can have impacts in many other solutions using the same rule and would require testing efforts.
For now, you can disable the rule "Execute rules for field Number_FixedPriceCurrency" and copy the other two rules from the source field "Number_FixedPriceCurrency" and copy them here.