While creating a custom connector for Power Automate, I'm getting the following error with the swagger (no validation errors are occurring & I have checked it via multiple editors),

The request failed with client error: '{"Code":"","Message":"GET https://power-apim-europe-001.management.azure-api.net/subscriptions/873e5639-9775-4e58-ac59-935e3f7dbc6c/resourceGroups/apim-power-europe-001/providers/Microsoft.ApiManagement/service/power-apim-europe-001/apis/smartsheet-20api-5f83fde20557d336df-5f8f194df2cac2ec5c?import=true&protocols=https&path=apim%2fsmartsheet-20api-5f83fde20557d336df-5f8f194df2cac2ec5c&api-version=2019-01-01&asyncId=623a42ef47fc0015e44853aa&asyncCode=201 failed with BadRequest, content={\"error\":{\"code\":\"ValidationError\",\"message\":\"One or more fields contain incorrect values:\",\"details\":[{\"code\":\"ValidationError\",\"target\":\"value[121].urlTemplate\",\"message\":\"URL template is invalid\"}]}}","Target":null,"Details":[],"Innererror":null}'. The correlation Id is '7eabc939-4c3f-484e-bdbd-b4568844c321'.

Pastebin - Swagger File (pasted to pastebin due to SO character limit for question body)

I seem to be banging my head against a brick wall now, as the error message isn't helpful at all. Can anyone spot whats wrong here?