I have uploaded almost 8K products using product CSV. Everything is working fine instead of collections. As i'm importing multiple products with same collection name.
So, as described in shopify documentation. When you import a product with collection name. Shopify add this product to existing collection with same name but if collection does not exist shopify create a new collection and add that product to new collection.
But in my case where multiple products have same collection name. Instead of creating one collection for all that products it creates different collection for each product even though with same name but different handles.
E.g: I have 5 products in my CSV file with same collection name in 'Collection' field ( suppose shoes ). So, according to shopify documentation it should just create one collection with named 'shoes' and should add all 5 products in that collection. but it's creating 5 collections with same name ( shoes ) one for each product. but with different handles (shoes, shoes-1, shoes-2 so on).