Google doesn't index a category of pages on a Wordpress website

Question

it's been probably a month from when we published new pages to improve the SEO of our website : o-matic.ch.

Google doesn't index those pages from the beginning and doesn't crawled them.

Our website is a wordpress and the pages are a category of archive.

The pages are the following :

• https://o-matic.ch/service/
• https://o-matic.ch/service/applications-mobiles/
• https://o-matic.ch/service/consulting/
• https://o-matic.ch/service/motion-illustrations/
• https://o-matic.ch/service/sites-applications-web/
• https://o-matic.ch/service/ux-ui/

We tried all we could find :

• Reupload the sitemap
• Ask to index (every day or 2/3 daysince the beginning)
• Test the page then ask to index
• Add internal link on our homepage (from the beginning) and other pages which are all previously indexed

Our last idea is to add linkrel="canonical" href="URL" on our pages but we don't know if it could help.

Have you another idea ?