coal inventory and furnace bug

coal disappears from inv and hot bar when selecting any furnace. cannot use coal in furnaces anymore except blocks of coal. i mined 1 coal and 34 coal appeared in inv and hot bar. tried again to use it in a furnace and it all disappeared again. rebooting tablet did not help. using v0.13.1 alpha. which "does not exist" but it does exist so i was forced to choose a random version from the drop down list to be able to report.