When "Godzilla vs. Kong” opened with weekend sales of nearly $70 million in China in March, it seemed the market would be a bright spot for Hollywood studios: most theaters were open, while U.S. film-goers were still staying home because of the coronavirus.

But 2021 is turning into a disappointment for movie companies in China, which passed the U.S. last year to become the world’s largest film market. U.S. films have grabbed about 15% of the box office, on par with pandemic-impaired sales in 2020 and far less than the 32% they claimed in 2019, according to data compiled by Bloomberg from the Chinese ticketing service Maoyan Entertainment.

Rather than becoming a lifeline for Hollywood, China is turning into another headache, made worse by local politics, the pandemic and the country’s complicated relationship with the U.S. President Xi Jinping’s efforts to emphasize Chinese nationalism and tamp down anything perceived as too Western or immoral will complicate matters for U.S. studios, possibly for years.