UTF-8 Checkboxes don't always get converted to PDF

[yennor]

I've had a document with some UTF-8 checkboxes. ☐ ☒
When converting the odt to pdf, none were converted (I had the same problem from DocX to PDF).
Then I chanced the font from Arial to Liberation Serif. And at once all were exported.
So I've created a sample document, with checkboxes in Arial and Liveration Serif, and in this example document, all the arial checkboxes are exported, but on of the liberation serif not. So no idea what the real problem is.
First i've used iText and then openPdf. Same result.
Anyway, document attached..

test.odt
result.pdf

pom.xml

		<dependency>
		    <groupId>fr.opensagres.xdocreport</groupId>
		    <artifactId>xdocreport</artifactId>
		    <version>2.1.0</version>
		</dependency>
		<dependency>
		    <groupId>fr.opensagres.xdocreport</groupId>
		    <artifactId>fr.opensagres.odfdom.converter.pdf.openpdf</artifactId>
		    <version>2.1.0</version>
		</dependency>

Code:

				Options options = Options.getTo(ConverterTypeTo.PDF).from(DocumentKind.ODT);
				IXDocReport report = XDocReportRegistry.getRegistry().loadReport(
						templateInputStream, TemplateEngineKind.Freemarker);
				IContext context = report.createContext();
				report.convert(context, options, odtOs);