After downgrading from Katalon Studio 7.2.1 to Katalon Studio 6.3.3 script execution with global variable is failing

After downgrading from Katalon Studio 7.2.1 to Katalon Studio 6.3.3 script execution with global variable is failing.

Error message in report says:
"Unable to delay browser (Root cause: java.lang.NumberFormatException: For input string: “null”
at com.kms.katalon.core.keyword.builtin.DelayKeyword$_delay_closure1.doCall(DelayKeyword.groovy:50)
at com.kms.katalon.core.keyword.builtin.DelayKeyword$_delay_closure1.call(DelayKeyword.groovy)
at com.kms.katalon.core.keyword.internal.KeywordMain.runKeyword(KeywordMain.groovy:68)
at com.kms.katalon.core.keyword.builtin.DelayKeyword.delay(DelayKeyword.groovy:48)
at com.kms.katalon.core.keyword.builtin.DelayKeyword.execute(DelayKeyword.groovy:43)
at com.kms.katalon.core.keyword.internal.KeywordExecutor.executeKeywordForPlatform(KeywordExecutor.groovy:56)
at com.kms.katalon.core.keyword.BuiltinKeywords.delay(BuiltinKeywords.groovy:375)
at LoginToSFDCFromOKTA.run(LoginToSFDCFromOKTA:39)
at com.kms.katalon.core.main.ScriptEngine.run(ScriptEngine.java:194)
at com.kms.katalon.core.main.ScriptEngine.runScriptAsRawText(ScriptEngine.java:119)
at com.kms.katalon.core.main.TestCaseExecutor.runScript(TestCaseExecutor.java:337)
at com.kms.katalon.core.main.TestCaseExecutor.doExecute(TestCaseExecutor.java:328)
at com.kms.katalon.core.main.TestCaseExecutor.processExecutionPhase(TestCaseExecutor.java:307)
at com.kms.katalon.core.main.TestCaseExecutor.accessMainPhase(TestCaseExecutor.java:299)
at com.kms.katalon.core.main.TestCaseExecutor.execute(TestCaseExecutor.java:233)
at com.kms.katalon.core.main.TestCaseMain.runTestCase(TestCaseMain.java:114)
at com.kms.katalon.core.keyword.builtin.CallTestCaseKeyword$_callTestCase_closure1.doCall(CallTestCaseKeyword.groovy:59)
at com.kms.katalon.core.keyword.builtin.CallTestCaseKeyword$_callTestCase_closure1.call(CallTestCaseKeyword.groovy)
at com.kms.katalon.core.keyword.internal.KeywordMain.runKeyword(KeywordMain.groovy:68)
at com.kms.katalon.core.keyword.builtin.CallTestCaseKeyword.callTestCase(CallTestCaseKeyword.groovy:81)
at com.kms.katalon.core.keyword.builtin.CallTestCaseKeyword.execute(CallTestCaseKeyword.groovy:44)
at com.kms.katalon.core.keyword.internal.KeywordExecutor.executeKeywordForPlatform(KeywordExecutor.groovy:56)
at com.kms.katalon.core.keyword.BuiltinKeywords.callTestCase(BuiltinKeywords.groovy:334)
at TC_Login_Impersonation_IP.run(TC_Login_Impersonation_IP:37)
at com.kms.katalon.core.main.ScriptEngine.run(ScriptEngine.java:194)
at com.kms.katalon.core.main.ScriptEngine.runScriptAsRawText(ScriptEngine.java:119)
at com.kms.katalon.core.main.TestCaseExecutor.runScript(TestCaseExecutor.java:337)
at com.kms.katalon.core.main.TestCaseExecutor.doExecute(TestCaseExecutor.java:328)
at com.kms.katalon.core.main.TestCaseExecutor.processExecutionPhase(TestCaseExecutor.java:307)
at com.kms.katalon.core.main.TestCaseExecutor.accessMainPhase(TestCaseExecutor.java:299)
at com.kms.katalon.core.main.TestCaseExecutor.execute(TestCaseExecutor.java:233)
at com.kms.katalon.core.main.TestSuiteExecutor.accessTestCaseMainPhase(TestSuiteExecutor.java:169)
at com.kms.katalon.core.main.TestSuiteExecutor.accessTestSuiteMainPhase(TestSuiteExecutor.java:142)
at com.kms.katalon.core.main.TestSuiteExecutor.execute(TestSuiteExecutor.java:91)
at com.kms.katalon.core.main.TestCaseMain.startTestSuite(TestCaseMain.java:157)
at com.kms.katalon.core.main.TestCaseMain$startTestSuite$0.call(Unknown Source)
at TempTestSuite1586488214256.run(TempTestSuite1586488214256.groovy:35)
) "

Why is this happening? How can i fix this issue?

Can you show us LoginToSFDCFromOKTA line 39?

Thanks jlegault. We found that the global variable profile had got reset and hence the defined variable was not fetched. We deleted the profile and recreated it once more and the problem solved.
Any idea why the profile of KS behaves this way?