According to National Geographic, the last surviving male Sumatran Rhino in Malaysia passed away and the sanctuary is now left with just one female, named Iman. 

Source: South China Post
Source: Free Malaysia Today

The male rhino, Tam, was found near an oil plantation in 2008. Since then, he was protected and had lived in the Tabin Wildlife Reserve in Sabah, Malaysia. Apart from the male, two female rhinos, Puntung & Iman, also dwelled in the sanctuary. 

Source: Livescience.com

Any hopes of breeding were dealt a blow in 2017 when Puntung died due to cancer. Now Iman is the only Sumatran Rhino that is alive in this Malaysian sanctuary. 

Source: Gulf Times

Blaming illegal poaching, loss of natural habitat and isolation as a reason for the hastened decline of the rhino population, a wildlife practice leader for WWF International, Margaret Kinnaird told National Geographic

Tam’s death underscores how critically important the collaborative efforts driving the Sumatran Rhino Rescue project are. We’ve got to capture those remaining, isolated rhinos in Kalimantan and Sumatra and do our best to encourage them to make babies.
Source: Unilad.co.uk

Speaking about the death of the last male Sumatran Rhino in their sanctuary, Margaret added: 

We hung so much hope on Tam to produce offspring in captivity, but that hope was dashed when the remaining two females at Tabin were unable to carry fetuses.
Source: Rojak Daily

With just over 80 Sumatran Rhinos living in the wild, it is a grave challenge for conservationists and sanctuaries to revive the population of these rhinos once again.