Prayer plant going downhill

[Marb67]

Well I just don't know why this once thriving plant has taken a decline as it just doesn't want to live. I have it in a warm spot, let the soil dry before watering (as advised) but it just looks pathetic.

Can anyone help me rescue yet another dying plant ?

Thanks

[Snoop Puss]

I've never had one, Marb, so not an expert. They look very pretty. Might the cultivation section of this website help? I notice no direct sunlight and minimum of 15 ºC at night. Might be a bit chillier than that if it's behind a curtain at night.
https://en.wikipedia.org/wiki/Maranta_leuconeura

[Marb67]

Aaaaaaand another one is biting the dust. Kept in normal conditions and no cold. This has been thriving for a while but suddenly (as with most plants I have) starts dying for no reason.

[Martin H]

They die for me too, Marb. If you find out how to keep them happy, please let us know!

[Marb67]

I have read prayer plants like to really dry out before watering. I also read prayer plants don’t like to dry out and need constant moisture. Why don’t these “experts” have a clue ? My soil has been moist but the end result is still death.