Cfgridupdate shifts columns by 1 - CF2018

Hello everyone, I'm currently having an issue when using cfgridupdate on a cfgrid, whenever I use it, all the columns are shifted by 1 (but not the headers). My code is almost identical to the one given in the adobe documentation of cfgridupdate (https://helpx.adobe.com/coldfusion/cfml-reference/coldfusion-tags/tags-g-h/cfgridupdate.html), so it should be working normally, but it's not. Here is below the code I'm using :

<!--- If the gridEntered form field exists, the form was submitted. Perform gridupdate. --->
<cfif IsDefined("form.gridEntered") is True> 
<cfgridupdate grid = "FirstGrid" dataSource = "cfdocexamples" Keyonly="true"
tableName = "COURSELIST"> 
</cfif> 
 
<!--- Query the database to fill up the grid. --->
<cfquery name = "GetCourses" dataSource = "cfdocexamples"> 
SELECT Course_ID, Dept_ID, CorNumber, CorName, CorLevel, CorDesc 
FROM CourseList 
ORDER by Dept_ID ASC, CorNumber ASC
</cfquery> 
 
<h3>cfgrid Example</h3> 
<I>Try adding a course to the database, and then deleting it.</i> 
<cfform> 
<cfgrid name = "FirstGrid" width = "450" format="html"
query = "GetCourses" insert = "Yes" delete = "Yes"
font = "Tahoma" rowHeaders = "No"
colHeaderBold = "Yes"
selectMode = "EDIT"
insertButton = "Insert a Row" deleteButton = "Delete selected row" > 
</cfgrid> 
<cfinput type="submit" name="gridEntered"> 
</cfform>...

I've seen that there have been issues with this tag in the past, but I never seen some concrete answer even for anterior versions of Coldfusion. Could any of you enlighten me on this, is this a known and solved issue or is it just me ?