IFM Manager plugin doesn't work after installing Appian 18.2 Hotfix T

Hello,

We just installed the 18.2 Hotfix on our Prelive environment and the IFM Manager plugin doesn't work. After debuging the problem, we found this part of code that doesn't work anymore:

public Object getExpressionResultForInstance(Long processInstanceId, String expression) throws InvalidProcessException, InvalidProcessVariableNameException, PrivilegeException, InvalidTypeException {
// Note: this could be made slightly more efficient if it checks if the same PV name is used multiple times
ArrayList<NamedTypedValue> tvList = new ArrayList<NamedTypedValue>();

Matcher matcher = pattern.matcher(expression);
String pvName;
ProcessVariableInstance pvi;

int variableIndex = 0;

/*geo LOG.finer(processInstanceId + " original expression: " + expression);*/
/*LOG.error(processInstanceId + " original expression: " + expression + "George step 1");*/
LOG.debug("George 1 "+ processInstanceId + " original expression: " + expression );

while (matcher.find()) {
pvName = matcher.group(1);

/*geo LOG.finer(processInstanceId + " found PV " + pvName + ". Param name will be " + VARIABLE_NAMES[variableIndex]);*/

pvi = getProcessVariableInstanceValue(processInstanceId, pvName, VARIABLE_NAMES[variableIndex]);

tvList.add(pvi);

expression = expression.replace(matcher.group(0), VARIABLE_NAMES[variableIndex]);

++variableIndex;
}

/*geo LOG.finer(processInstanceId + " final expression: " + expression); */
/*LOG.error(processInstanceId + " final expression: " + expression + "George step 2");*/
LOG.debug(processInstanceId + " final expression: " + expression);

PartialResult rep = pds.evaluateExpressionInVariableContext(expression, tvList.toArray(new NamedTypedValue[] {}), null);

return rep.getResult().getValue();
}

I added some logs, but couldn't find out the problem. Those anyone has this problem also? Can someone help with some info about the differences between the sdk and jar from Appian 18.2 Hotfix J and Appian 18.2 Hotfix T.

Thanks in advance,

George