A reminder that changes to the UI config are not covered under SMA, they are covered under Professional Services which you may have bought a block of hours (lower price typically) or may be pay-as-you-go. Fortunately there are tools (exporting the preferences to view, importing them to 'fix up' mistakes) to lower the cost when you do make a mistake.

"My Assigned Work" is an offline query and we always apply arbitrary sanity limits to offline data. But you can change the 'sanity' limits if your situation warrants. So taking the Work Order My Assigned Work query as an example, in the system preferences:

Since this is a system default it is pulled from the database via Query Engine here:

All non-offline queries are "infinite" with implicit paging to load data as you scroll. The difference is that "My Assigned Work" has to be 100% read and transferred on sync which means it is always looked at (performance) so we have always had a limiter present in order to constrain accidental DDOS due to mistakes.

Either of those places can "fix" the problem. Changing the query assignments has the downside of new queries don't auto-add, changing the query itself has the downside of it being a system query and thus will often be wiped and re-loaded on upgrade.