There are no issues with Airbnb in Barcelona. For the past couple of years Airbnb, HomeStay and a few others arrogantly thought they could go by without complying with local laws. They soon found out they could not, and after a few heavy fines they decided to adhere to the Barcelona City Council regulations to be able to continue operating (in one of their most lucrative markets) and now they allow only offers of legally registered apartments to be published in their portals. Now they operate smoothly and without any problems. So you know.
Whenever you look for an apartment in these portals, ensure they present the HUB number (the license) which indicates this apartment is complying with the local laws and is duly registered in the database of tourist accommodations: https://meet.barcelona.cat/habitatgesturistics/en
For clarity: this applies to rentals of "whole apartments" (not rooms). For the later, the City Council has promised to issue a different adapted regulation later this year in order to organize the existing offer and to protect both consumers and residents of the city.