Grammar related to أصحاب الأيكة?

أصحاب الأيكة, translated as "people of the wood" or "people of the forest", is a phrase that occurs 4 times in the Holy Quran. It refers to the people of Shuaib (as). However, there is a discrepancy in the spelling of the word "اَلْأَيْكَة". Twice it is seen as it should be (الأيكة) but twice it shows up as "لْئَيْكَة" which is still pronounced the same but it does not have the hamza wasl. 15:78,50:14 – اَلْأَيْكَةِ(with hamza wasl) 26:176 38:13 – لْئَيْكَةِ (without hamza wasl) What I've gathered from going through tafasir on the matter is that this discrepancy is due to an alternate qira'at present at those 2 places where the word is ممنوع من الصرف and is pronounced أَصْحَابُ لَيْكَةَ upon the wazn of لَيْلَةٌ. However, thus far I can't answer the following questions: 1. Why is this alternate Qirat only present at 2 of the 4 locations? 2. Why/how does removing the hamza wasl indicate the alternate Qirat even though it is still pronounced the same? 3. Why is there this middle ground between accepting the Qirat and having it pronounced as "لَيْكَةَ" at the 2 spots and keeping it normal? (Middle ground being pronouncing it normally but indicating the qirat by a slight change of spelling). This is by no means an allegation against the Quran (nauzu billah). I firmly believe in the Quran and will bear witness to its truthfulness until my last breath (Insha'Allah). But I've had this question on my mind for a long time and haven't come up with a fulfilling answer. If anyone knows anything in this regard I would much appreciate their help.