▲ 譚處端: 《水雲集》, 明刻本, 卷上, folio 14B



▲ 譚處端: 《水雲集》, 正統道藏, 卷上

The text of this poem shows below.
遊懷川 譚處端
雲耕寶陸三千里 [平平仄仄平平仄]
月破黄昏十萬家 [仄仄平平仄仄平/韻]
清夜碧潭澄皎潔 [平仄仄平平仄仄]
蚌吞銀～産胎砂 [仄平平仄仄平平/韻]
It is very easy to know the tone of this character must be 仄 not 平.

Other version shows 焰, which matches 仄.

▲ 顧嗣立: 《元詩選》, 文淵閣四庫全書, 二集, 卷二十五, folio 3A