rich:modalPanel doesn't show up anymore if h:commandButton was clicked

First of all, this issue is on Edge only, everything works just fine on Chrome and Firefox.

I'm working with JSF 1.2 and RichFaces 3.3.3.Final (with community fix for IE9+).

I have a rich:modalPanel which is opened by a a4j:commandButton. On the modal panel there is a h:commandButton which hides the modal panel and exports a pdf generated with jasperReports. My issue is that after exporting a file for the first time, the modal panel doesn't show up anymore. I have to reload the page and then it works again. There's nothing new in console when I press a4j:commandButton to open the modal panel, the last log is "HTML1300: Navigation occured." which comes from pressing h:commandButton.

Open modal panel (contents.jspx) - sets printBean.showModalPanel to true:

<a4j:commandButton
    image="/img/print.gif"
    styleClass="clsCursorPointer"
    action="#{ printBean.onExportReport}"
    ajaxSingle="true"
    reRender="printConfirmationPanel" />

Modal panel (forms.jspx):

<h:panelGroup id="printConfirmationPanel" >
    <rich:modalPanel id="printConfirmationMP"
        autosized="true"
        showWhenRendered="true"
        rendered="#{ printBean.showModalPanel}" >
        <h:form>
            <h:panelGrid columns="2" style="margin: auto">
                <h:commandButton id="confirmButton"             <--- Export button
                    value="#{ msgs['printButton']}"
                    actionListener="#{ printBean.onExportButton}" >

                    <f:attribute name="format" value="PDF"/>
                    (more attributes)
                </h:commandButton>

                <rich:componentControl
                    attachTo="confirmButton"
                    for="printConfirmationMP"
                    operation="hide"
                    event="onclick" />
            </h:panelGrid>
        </h:form>
    </rich:modalPanel>
</h:panelGroup>

Problem is solved by updating Edge to version 81.0.416.53.