Config Export for Matomo is empty even though it is in the JSON file

[yorkshire-pudding]

Not sure if this is a core issue or with the module. It doesn't seem to affect other modules.

Steps to reproduce

1. Configure Matomo
2. Navigate to admin/config/development/configuration/single/export
3. Select 'Configuration' under 'Configuration group'
4. Select 'Matomo' under 'Configuration name'

Expected result
Config as per the JSON file

{
    "_config_name": "matomo.settings",
    "site_id": "1",
    "url_http": "http://analytics.example.co.uk/",
    "url_https": "https://analytics.example.co.uk/",
    "domain_mode": "0",
    "visibility_pages": "0",
    "visibility_roles": "1",
    "roles": {
        "administrator": "administrator",
        "anonymous": 0,
        "authenticated": 0,
        "editor": 0
    },
    "custom": "1",
    "trackuserid": 1,
    "trackmailto": 1,
    "track": 1,
    "trackfiles_extensions": "7z|aac|arc|arj|asf|asx|avi|bin|csv|doc(x|m)?|dot(x|m)?|exe|flv|gif|gz|gzip|hqx|jar|jpe?g|js|mp(2|3|4|e?g)|mov(ie)?|msi|msp|pdf|phps|png|ppt(x|m)?|pot(x|m)?|pps(x|m)?|ppam|sld(x|m)?|thmx|qtm?|ra(m|r)?|sea|sit|tar|tgz|torrent|txt|wav|wma|wmv|wpd|xls(x|m|b)?|xlt(x|m)|xlam|xml|z|zip",
    "trackcolorbox": 1,
    "trackmessages": {
        "status": "status",
        "warning": "warning",
        "error": "error"
    },
    "site_search": 1,
    "privacy_donottrack": 1,
    "page_title_hierarchy": 1,
    "page_title_hierarchy_exclude_home": 0,
    "custom_var": {
        "slots": {
            "1": {
                "slot": 1,
                "name": "",
                "value": "",
                "scope": "visit"
            },
            "2": {
                "slot": 2,
                "name": "",
                "value": "",
                "scope": "visit"
            },
            "3": {
                "slot": 3,
                "name": "",
                "value": "",
                "scope": "visit"
            },
            "4": {
                "slot": 4,
                "name": "",
                "value": "",
                "scope": "visit"
            },
            "5": {
                "slot": 5,
                "name": "",
                "value": "",
                "scope": "visit"
            }
        }
    },
    "cache": 1,
    "last_cache": 1641899888,
    "translation_set": 0,
    "codesnippet_before": "",
    "codesnippet_after": "",
    "js_scope": "header",
    "pages": "admin\r\nadmin/*\r\nbatch\r\nnode/add*\r\nnode/edit/*\r\nuser/*/*",
    "url_skiperror": "",
    "tracking__active_tab": ""
}

Actual result
Export config is blank except header

[indigoxela]

@yorkshire-pudding many thanks for reporting, that's a bug in this module (wrong prefix in hook_config_info), the latest commit should fix it.