The Application installed on customer not responding on developer environment working properly

Question

My application working, with limitation of a beginner in Visual Studio C# programmer, working properly from 10 months.

After last security updates of March the application not responding.

I have developped three programs:

the first program is a application that download from a ftp site a file and load data into a DB table.

The second every 5 seconds read last record from a DB Table and show it on a DatagridView, read a second DB Table and put the result in a second DataGridView and as third activity read another DB table and put the result into a third datagridview on the same window.

The Third is more complex is a planning program and anable the user to plan activity reading the first DB table where are located information written from the fisrt program, have possibility to transfer the record readed to the second DB Table after ordered the sequence. At the same time read the last record on the third DB table every 5 seconds and show it to the user.

After performed security updateds at the middle of march my programs don't works properly.

The second program not responding and don't show info on windows form but working properly, I hve verified it with the log.

The Third program, that require user interaction, working properly but often not responding and the user must kill and restart it.

I suppose that the problem is related at the graphical user interface and how I use it.

Unfortunately I don't found how investigate to solve it.

Can you help me to debug the problems?

The Debug need to be done on customer environment because on my environment I don't have probems.

Before ask your help I have updated application to use .net 8.

The customer have Azure Domain with Intune and Defender with many policys applied.

How I can do a Run Time debug of application?

Thanks in advance for your help