Maybe try "Use new subtitle parser/renderer"
{Novo método de leitura e renderização de legendas} under
(rightclick >) Options > Preferences > Subtitles [Subtitle properties]
{(mouse direita >) Opções > Preferências > Legendas [Propriedades]}
(
While you're there ... is "Enable drawing subtitles under image with EVR renderer" selected... this assuming that you're using EVR (Enhanced Video Renderer) under Preferences > Video > [Video rendering])
Type of subtitles, type of movie-file?
Maybe read items (3) and (9) of my Help2help-post.