Erroneous Value returned, Any Ideas?

I have a problem that seems to be a C++ version issue but not a sufficient background to choose vocabulary and labels necessary to lookup or identify my issue.

I have to compile my application on a school server using C++11, but I edit on Replit:

clang++-7 -pthread -std=c++17 -o main Car.cpp CarWash.cpp main.cpp

I run the application on Replit and all values come out fine.

I run the application on the school server and there are incorrect values that occur at specific places in the data processing. So I examined the data. (It is just a text file with a number, newline, number, newline, etc.)

When I call an int return method on a class using a pointer with an arrow operator, only 2 out of 100 values are incorrect. If the int return method should return a small value 0-10 range (but not consistently) I get 281 and then later 47. I tried some casting options to see if that was the issue and also verified the object's values were not strange.

The culprit I think is the math function in car->getWait(); (a simple subtraction problem)

The method is written as:

int Car::getWait() 
{ 
  return washStart - timeArrived;
}

I even made other return methods and vars so I could return washStart and timeArrived separately to perform the operation, then use cout to display. I get the same specifically large wrong number at specific places while the rest of the operations work fine.

Replit Output:

	Returned
41	0.000000
42	2.000000
43	4.000000
83	2.000000
84	0.000000
85	1.000000

Server Output:

	Returned
41	0.000000
42	281.000000
43	4.000000
83	2.000000
84	37.000000
85	1.000000

Car.h

Car.cpp