Selenium couldn't find an element inside the iframe - selenium

Question

I am creating an automated test cases for this page https://cloud.google.com/products/calculator in scope of my practical task using Selenium + Java.
At some point I've faced with a problem when the WebDriver couldn't find an element inside the iframe, even if in the previous test case I was able to interact with the elements of this iframe.
All my test cases are running one by one without closing the driver and each next test case can passed only if the previous test case passed as well.
Here is my GitHub repo:
https://github.com/SerhiiVeselov/hurt-me-planty.git
Here are my test cases:
#BeforeAll
public static void driverSetup() {
driver = new ChromeDriver();
driver.manage().window().maximize();
mainPage = new MainPage(driver);
searchResultsPage = new SearchResultsPage(driver);
pricingCalculatorPage = new PricingCalculatorPage(driver);
fluentWait = new FluentWait<>(driver)
.withTimeout(Duration.ofSeconds(10))
.pollingEvery(Duration.ofSeconds(2))
.ignoring(NoSuchElementException.class);
}
#Test
#Order(1)
#DisplayName("Search of the Pricing Calculator page")
public void openPricingCalculator() {
mainPage.openPage();
fluentWait.until(ExpectedConditions.visibilityOf(mainPage.getCookiesOkBtn()));
mainPage.closeCookiesPopUp();
mainPage.openSearchField();
mainPage.enterSearchRequest();
fluentWait.until(ExpectedConditions.visibilityOf(mainPage.getSuggestSearchResult()));
mainPage.clickSuggestSearchResult();
fluentWait.until(ExpectedConditions.visibilityOf(searchResultsPage.getSearchResultsTab()));
searchResultsPage.clickPricingCalculatorLink();
assertEquals("https://cloud.google.com/products/calculator", driver.getCurrentUrl());
fluentWait.until(ExpectedConditions.frameToBeAvailableAndSwitchToIt(pricingCalculatorPage.getCloudSideFrame()));
fluentWait.until(ExpectedConditions.frameToBeAvailableAndSwitchToIt((pricingCalculatorPage.getMyFrame())));
}
#Test
#Order(2)
#DisplayName("Fill the Calculation Form")
public void fillCalculationForm() {
pricingCalculatorPage.enterNumberOfInstances();
pricingCalculatorPage.selectOperatingSystem();
pricingCalculatorPage.selectProvisioningModel();
pricingCalculatorPage.selectMachineType();
pricingCalculatorPage.checkAddGpuCheckBox();
pricingCalculatorPage.selectGpuType();
pricingCalculatorPage.selectGpuQuantity();
pricingCalculatorPage.selectLocalSsd();
pricingCalculatorPage.selectDatacenterLocation();
pricingCalculatorPage.addToEstimate();
fluentWait.until(ExpectedConditions.visibilityOf(pricingCalculatorPage.getTotalEstimatedCost()));
assertEquals("Instance type: n1-standard-8", pricingCalculatorPage.getInstanceTypeTest().getText());
}
#Test
#Order(3)
#DisplayName("Check the name of the Machine type")
public void verifyMachineType() {
assertEquals("Instance type: n1-standard-8", pricingCalculatorPage.getInstanceTypeTest().getText());
}
Here is the webpage for which I've created 2d and 3d test cases: https://cloud.google.com/products/calculator
page for automation in 2d and 3d test cases
So far, 1st and 2d test cases are passing and working as expected. But 3d test case is failing all the time cause the WebDriver couldn't find the element from the getInstanceTypeTest method:
org.openqa.selenium.NoSuchElementException: no such element: Unable to locate element: {"method":"xpath","selector":"//div[contains(text(), 'Instance type')]"}
Most of elements I interested in are located inside the same iframe (id=myFrame).
I have a selector for instanceTypeTest WebElement creared using xpath //div[contains(text(), 'Instance type')].
In 3d test case I want to check this field and get from it a text value to compare it with the value which was selected at the left form at https://cloud.google.com/products/calculator page.
I guess, after I filling the left form with data and clicking the 'ADD TO ESTIMATE' button something is happening with the iframes or the driver is loosing it's focus to the right frame.
I tried to add at the beginning of the 3d test case some code which should take driver back to the default web page content and then switch driver to outer iframe (cloudSideFrame) and after that - to inner iframe (myFrame):
driver.switchTo().defaultContent(); fluentWait.until(ExpectedConditions.frameToBeAvailableAndSwitchToIt(pricingCalculatorPage.getCloudSideFrame())); fluentWait.until(ExpectedConditions.frameToBeAvailableAndSwitchToIt((pricingCalculatorPage.getMyFrame())));
It didn't help me. Driver still couldn't find Instance type field.
I can't understand why driver could find some elements inside the iframe even if it could find some others inside the same iframe.
Please help me to solve this problem.