Cloudflare make a best guess about what DNS records you already have on your old hosting provider, and add them during the add zone process. There is no way that Cloudflare can know every record you have on your old DNS servers.
I don’t know if CF even attempt an AXFR transfer, which would capture everything, but most DNS servers do not support zone transfers.
You can import a BIND format zone file into Cloudflare, so if your old provider can export this format you will capture everything.
Cloudflare does a scan of common records. When the scan is complete it asks the person signing up to verify that all the records needed are there. While I understand it can be difficult to experience downtime because you missed a record, you may want to use a BIND export of your current settings in the future when adding a domain to Cloudflare https://support.cloudflare.com/hc/en-us/articles/200168856-Importing-and-exporting-DNS-records
Records created on Cloudflare generally propagate Globally in under 30 seconds. It is likely a caching issue with the DNS server you have configured in your wifi system which prevents the lookup, but that is not something Cloudflare can control.
@Xaq Now records are running okay, incase of any assistance, will get back to u.
@michael i did not had access to customers previous NS servers, so could not request for export. Will keep in mind for next website.
@OliverGrant My all other websites i have added till date worked perfect with all the records pulled, however this came up as a surprise when client complained about the downtime. For DNS cache i will recheck my local DNS.
Thank you all for the inputs, will get back if i face any issue.