Navigation sidebar is empty even though my resources have a navigation group

Hello,
I am experiencing a weird behavior on my admin panel's sidebar where the navigation groups appear empty even if in my resources' files I have correctly set the navigation icon and navigation group.

The error that comes up is:

hook.js:608 Alpine Expression Error: Cannot read properties of null (reading 'includes')

Expression: "! $store.sidebar.groupIsCollapsed(label)"

hook.js:608 Alpine Expression Error: Cannot read properties of null (reading 'includes')

Expression: "! $store.sidebar.groupIsCollapsed(label)"

and:

module.esm.js:442 Uncaught TypeError: Cannot read properties of null (reading 'includes')
    at Proxy.groupIsCollapsed (app.js?v=3.2.117.0:1:6688)
    at [Alpine] ! $store.sidebar.groupIsCollapsed(label) (eval at <anonymous> (http://dive360.panosaridis.gr/livewire/livewire.min.js?id=cc800bf4:5:668), <anonymous>:3:49)
    at module.esm.js:516:21
    at Ol (module.esm.js:428:12)
    at module.esm.js:3093:17
    at r (module.esm.js:1787:16)
    at Object.Ou [as effect] (module.esm.js:1762:5)
    at Te (module.esm.js:51:33)
    at module.esm.js:67:27
    at Function.<anonymous> (module.esm.js:3093:3)

module.esm.js:442 Uncaught TypeError: Cannot read properties of null (reading 'includes')
    at Proxy.groupIsCollapsed (app.js?v=3.2.117.0:1:6688)
    at [Alpine] ! $store.sidebar.groupIsCollapsed(label) (eval at <anonymous> (http://dive360.panosaridis.gr/livewire/livewire.min.js?id=cc800bf4:5:668), <anonymous>:3:49)
    at module.esm.js:516:21
    at Ol (module.esm.js:428:12)
    at module.esm.js:3093:17
    at r (module.esm.js:1787:16)
    at Object.Ou [as effect] (module.esm.js:1762:5)
    at Te (module.esm.js:51:33)
    at module.esm.js:67:27
    at Function.<anonymous> (module.esm.js:3093:3)

I have set the navigation icon and group in my resources like this:

protected static ?string $navigationIcon = 'mdi-diving-scuba-flag';
    
protected static ?string $navigationGroup = 'On-line';

protected static ?string $navigationIcon = 'mdi-diving-scuba-flag';
    
protected static ?string $navigationGroup = 'On-line';

Any help? Thanks a lot.