I used to put mine out during the summer and they were usually ok. Have you given them a feed recently, if not that could be the problem. Have they got dried out too much as they are really happier in moist atmospheres. Also they do not do well in full sun.

AFAIK they are houseplants, like a lot of houseplants probably OK outside for a summer holiday & fresh air in the summertime only

Will keep them indoors for now, maybe sun was too strong?

They definitely don't like the full sun, dappled shade would be lovely. I have two indoors, one in a corner where it gets light but not full sun, the other gets more light and some sun and it doesn't like it! It has paler green leaves and just looks sadder. Must be kinder and move it somewhere else.