I imagine bigger clubs have the resources to ensure all (or most) possible visa issues are taken care of well in advance.
Its probably more common these days because there are a huge number of teams participating in Euro competitions these days, and wide range of countries to visit.
Then there are the politics that mean some countries are applying more rigour (to put it politely) to their visa and immigration processes. Brexit didn't help either, although that won't be the issue for Said, but citizens from countries such as Nigeria or India often face more hurdles.
Most visa challenges can be resolved, but it's the quick turnaround for football matches that is the problem. If you need to make an appointment with someone to answer questions or discuss the application it can be too late as those can takes weeks or months to arrange.
It's also probably more common in recent times because teams have players from around the globe. 30 or 40 years ago most teams had players that were home grown with only a handful at most of overseas players, and most of those players were European.