Odd issue with WPF controls in Add_Click not working up top - wpf

Question

First off, I'm a PowerShell guy, no experience in C# or with WPF applications aside from incorporating .NET WPF application templates from Visual Studio, so I apologize if my terminology is wrong or I'm not explaining this well.
I've built a small handful of GUI tools for my organization to use, pretty basic stuff and I haven't had any issues like this before - the workflow is essentially my Add_Click script block is supposed to start off by changing a progress bar with value of 0, to indeterminate ($true) and set a progress bar label content to "Running" → some proprietary functions that connect to our environment's API kick off → outputs results and the progress bar label content is set to "Complete" and the progress bar changes to not indeterminate ($false) with a value of 100.
The very bizarre issue that I cannot figure out, is the progress bar indeterminate doesn't get set to $true, the label doesn't change...but the functions all execute just fine, and the progress bar label at the end DOES change, and the progress bar at the end changes as well. Below is the sample code (full code not included because of the proprietary functions that wouldn't make sense, and the rest is just template code that imports the XAML).
XAML starts with $var_progLabel.Content set to "Ready", $var_progBar.IsIndeterminante set to $false.
$var_buttonRun.Add_Click({
# THESE TWO CONTROLS DON'T EXECUTE
$var_progLabel.Content = "Running..."
$var_progBar.IsIndeterminate = $true
<#
API CALL HERE TO GET DATA AND STORE IN $statusOutput - ALL RUNS SUCCESSFULLY
#>
# ALL BELOW RUNS SUCCESSFULLY
$var_progLabel.Content = "Complete!"
$var_progBar.Value = 100
$var_progBar.IsIndeterminate = $false
$statusOutput | Out-GridView
})
So TL;DR I guess, the top 2 controls in my Add_Click script block don't do anything, but everything else below does, include the same controls called at the bottom of the Add_Click. I'm just wondering if someone can educate me on the limitations of an Add_Click script block, or how/the order it processes data?

Answer 1

Not entirely sure, but it seems your issue is that your ProgressBar is blocked by another process, since both are running on the same thread. what you could
try is to run the API CALL on another thread as a Task:
private async Task<resultType> DoAPICallAsync()
{
//API CALL HERE TO GET DATA AND STORE IN $statusOutput - ALL RUNS SUCCESSFULLY
}
private async Button_Click(object sender,Arg...)
{
//Initialize your progress bar
await DoAPICallAsync();
//Set Progress bar to complete values
}