Most probably the issue occurs due to OCR Engine update.
General accuracy on a large number of documents will be higher for the new version - we know this because we’ve tested the improvements on tens of thousands of real documents. However, the OCR result for particular images can differ from the results received using the previous version, because OCR algorithm is not a simple one. It is a very sophisticated artificial intelligence algorithm, and even a small change in it influences the outcome.
For the receipt capture we recommend either to use the special API, which is currently in beta-testing, or the textExtraction profile (if the text order will be wrong, you can sort the words on your side using its coordinates from XML). Unfortunately, the default (documentConversion) profile is not suitable for this task, even if it worked before: it is designed for document recognition.