Custom Plugin: Can't navigate between reference and declaration

I am currently working on a Tapestry plugin for IntelliJ. The goal is to be able to jump back and forth between the Java file containing the Tapestry events and the template file (.tml).

Current problem:

I can currently jump from the Tapestry event, “t:event=”foo” to the ‘onFoo’ method in Java. However, it tells me that the “onFoo” method has no usages, so I can't jump from the method back to the TML file.

I've been sitting here for several days now and am totally exasperated because I don't understand why this doesn't work.

Here are some Snippets from my Code:

TapestryEventReferenceContributor:

public class TapestryEventReferenceContributor extends PsiReferenceContributor {

    @Override
    public void registerReferenceProviders(@NotNull PsiReferenceRegistrar registrar) {
        ElementPattern<XmlAttributeValue> pattern = XmlPatterns.xmlAttributeValue()
                .withParent(XmlPatterns.xmlAttribute()
                        .withName(string()
                                .oneOf("event", "t:event"))
                        .inFile(psiFile()
                                .withName(string()
                                        .endsWith(FileExtensions.TML.extension()))));

        registrar.registerReferenceProvider(
                pattern,
                new TapestryEventReferenceProvider()
        );
    }
}

TapestryEventReferenceProvider:

public class TapestryEventReferenceProvider extends PsiReferenceProvider {

    @Override
    public PsiReference @NotNull [] getReferencesByElement(@NotNull PsiElement element, @NotNull ProcessingContext context) {
        if (!(element instanceof XmlAttributeValue attrValue)) {
            return PsiReference.EMPTY_ARRAY;
        }

        String eventName = attrValue.getValue();
        if (eventName.isEmpty()) {
            return PsiReference.EMPTY_ARRAY;
        }

        TextRange range = new TextRange(0, attrValue.getValue().length() + 1);

        return new PsiReference[]{
            new TapestryEventReference(attrValue, range, eventName)
        };
    }
}

TapestryEventReference:

public class TapestryEventReference extends AbstractTapestryPsiReference {

    private static final Logger logger = Logger.getInstance(TapestryEventReference.class);

    private final String eventName;

    public TapestryEventReference(
            @NotNull XmlAttributeValue element,
            TextRange range,
            String eventName
    ) {
        super(element, range);
        this.eventName = eventName;
    }

    @Override
    public @Nullable PsiElement resolve() {
        logger.info("(resolve) => called");

        PsiFile tmlFile = myElement.getContainingFile();
        Optional<PsiFile> javaFile = TapestryUtil.findCorrespondingFile(myElement.getProject(), FileExtensions.JAVA, tmlFile);

        if (javaFile.isEmpty() || !(javaFile.get() instanceof PsiJavaFile file)) {
            logger.warn(String.format("(resolve) => can't find file '%s'", tmlFile.getName()));
            return null;
        }

        PsiClass[] classes = file.getClasses();
        for (PsiClass psiClass : classes) {
            var foundOnMethod = findTapestryOnMethod(psiClass, eventName);

            if (foundOnMethod.isPresent()) {
                return foundOnMethod.get();
            }
        }

        logger.warn(String.format("(resolve) => no method found for event '%s'", eventName));
        return null;
    }

    @Override
    public Object @NotNull [] getVariants() {
        return PsiReference.EMPTY_ARRAY;
    }
}

AbstractTapestryPsiReference:

public abstract class AbstractTapestryPsiReference extends PsiReferenceBase<PsiElement> {

    private static final Logger logger = Logger.getInstance(AbstractTapestryPsiReference.class);

    public AbstractTapestryPsiReference(@NotNull PsiElement element, TextRange range) {
        super(element, range);
    }

    // [...] implemented methods for finding methods in the Tapestry components Java file
}

How can it be that it does not find the usages of a method, but jumps there from the reference? Can someone explain this to me? How do I debug such problems? I have already noticed in the PSI viewer that the reference to the PsiElement:XML_ATTRIBUTE_VALUE (i.e. the “foo” in the TML file) is defined, but is displayed in red.