Modern browsers are increasingly designed to inhibit Third-party cookies.
Third-party cookies are frequently abused by websites. Some of the more backward desktop browsers, such as Chrome, are not designed to protect your privacy (in fact, often quite the reverse) - although Google have recently indicated that they too will soon adopt the new standards and block this pernicious tracking and cookie abuse.
Safari, being a privacy focussed browser, in blocking third-party cookies, is working entirely as intended. You don’t have a fault; nothing is broken - other than the “bad” website(s) that force use of third-party cookies with intent to compromise your privacy. The best advice is to avoid such websites.
It remains possible, although not recommended, to allow third-party cookies. This is an advanced setting - that should only be altered if you know what you’re doing - and that you accept that you are deliberately removing a significant layer of security protection from your iPad.
Settings > Safari > Advanced > Experimental Features > Disable Full 3rd Party Cookie Blocking (ITP) - set to ON
This screenshot illustrates the default (secure) setting - where third-party cookies are blocked.
Again, I must stress that you change this setting at your own risk.
Subject to your understanding and acceptance of the clear warnings given, I hope this information is helpful to you.
