There is the reason why Shopify orders do not show up on the Topdser Orders page.
Topdser only syncs Shopify orders that have been paid.
Then you can see the order which has been paid on the Topdser order page.
When your Shopify order is pending or in Drafts, these orders will not be synced to Topdser.
Make sure you choose the correct time range of Orders
For example, for the orders outside 2020-9-23 ~ 2020-10-23 will not appear in awaiting order list.